This past Monday saw the release of the second full-length trailer for Terminator: Genisys, the awfully titled, fifth big-screen installment in the James Cameron-originated sci-fi franchise that helped make Arnold Schwarzenegger a global superstar. That fact alone is hardly stunning, because April is typically a launching ground for pre-release peeks at the summer’s biggest, loudest, most expensive would-be blockbusters.

Far more noteworthy, however, is that, without warning or restraint, the new Terminator: Genisys trailer gives away a major—if not THE major—plot twist from the film’s story [one that I will not re-spoil, but if you like, check out the trailer for yourself here]. In short: It goes a long way toward ruining the very thing it’s selling.

Were this the exception to the rule, it would be easy to dismiss it as merely an awkward blunder on the part of Paramount Pictures. The problem is, it’s no exception, and no blunder. On the contrary, Genisys’ desire to divulge crucial narrative secrets months in advance of the film’s debut is a deliberate, calculated strategy, and one that’s in keeping with custom by the big studios when it comes to their tent-pole offerings—namely, to give consumers as much preview content as possible, regardless of the fact that, in the process, they’re undermining the very movies they’re promoting.

Take, for instance, Avengers: Age of Ultron, that obscure little film Marvel is releasing May 2. If memory serves, it’s a sequel to an earlier superhero team-up movie from 2012, though I’m not quite sure, because so far, I’ve only been able to watch close to a half-hour of the actual film thanks to a veritable onslaught of trailers (three), TV commercials (14 and counting), and out-of-context extended clips and promotional featurettes (at least 10). Sarcasm aside, this is insane. Studios have long been believed that the more audiences know about what they’re paying to see, the more likely they are to actually do so—and thus, from Carrie to Cast Away to What Lies Beneath, they’ve let things slip in trailers that were best left undisclosed. Even by usual standards, though, Marvel’s Ultron campaign has been egregious, functioning as one long, drawn-out drip of important footage and information. As handily summarized by Comic Book Resources, anyone with an Internet connection has access to a wealth of that movie’s centerpiece sequences and key characters in action.

Will this avalanche of spoilers in any way harm Ultron’s box-office performance? Of course not. And in fact, the studio is confident that by serving up constant breadcrumbs from their films, they’re actually maintaining—if not outright stoking—anticipation and excitement that will eventually drive people to theaters. That’s also true of Jurassic World, and this December’s Star Wars: The Force Awakens (whose second trailer premiered Thursday morning at Disney’s streamed-for-the-Internet Star Wars Celebration event, and featured that Darth Vader shot), and next March’s Batman v Superman: Dawn of Justice (whose maiden teaser arrived Thursday). Films like these can give away as much as they want, and it’s likely that not a single person will be deterred from forking over big money to see them.

Yet that’s the very reason they (and their studios) should do the opposite. Whether Ultron, Jurassic World, and The Force of Awakens release one trailer or 10, people will flock in droves to their local multiplex come opening weekend. As a result, the benefit of spoiling the films beforehand is, from a purely financial standpoint, negligible. Devout fanboys are already in the can when it comes to beloved genre properties. And casual moviegoers don’t need this much pre-release hype in order to have an opinion about, or impulse to attend, a given movie—a plot summary and one effectively crafted trailer is enough to do the trick. Providing more than that is overkill, plain and simple, and merely the studios’ way of calming their nerves. It’s insurance.

But more crucially, it’s unnecessary overkill that just about murders the actual moviegoing experience. One of the fundamental thrills afforded by movies is surprise. That moment when a story takes a sudden detour into unforeseen territory. When an unexpected character makes an out-of-left-field appearance. When a climax escalates in terms of scope, scale, and tension until you find yourself catching your breath. When an astonishing image abruptly knocks you flat, making your jaw drop, your stomach sink, or your eyes tear up. When you witness something you never thought you’d ever actually see outside of your imagination, or something that harkens back to a prior movie—or an incident in your own life—and the effect is so powerful and direct that it immediately becomes unforgettable.

Those are the moments that make the movies so special, and it’s those moments that are lessened, if not outright sullied, by the daily glut of clips and photos labeled “Exclusive!” and “Never-Before-Seen!” and “First Look!” While the studios are primarily responsible for overloading us with spoiler material, the Internet (and many of its entertainment and film-related sites) is also partly to blame. Promoted to the hilt on Twitter, Facebook, and other social-media channels by a range of publications—from mainstream sites to those that specifically court die-hard devotees of superhero, sci-fi, and fantasy fiction—this content is used to prey upon fans’ anticipation, to their own detriment. There’s no journalistic reason to republish a movie’s every new promo tidbit; doing so is little more than collaboration with a studio’s PR department. But there’s a very good reason to not behave in this way: because, akin to reading the last page of a book before you’ve started it (or an in-depth review before you’ve seen a film, play, or TV show), it destroys the potential for the very amazement, disbelief, anxiety and awe that is a central component of watching movies.

Moreover, it fosters a culture in which everyone expects—and demands—that they get everything NOW, ahead of time, and in as comprehensive a way as possible (see: piracy). It turns movie fandom into an arena of selfishness, and entitlement, and greed. And it won’t stop until everyone begins demanding less of what they want.