Here's the thing.
Jump scares, in my opinion, are simulated terror. They basically take advantage of the "fight or flight" instinct by introducing an abrupt, startling stimulus to induce that state in the audience.
Real terror is the kind that stays with you after the movie. You know why people so loved The Ring when it first came out? Because it was ****ing creepy as hell. It created real fear. Like, the kind that makes you go home and unplug your computer monitor and TV for the night....juuuuuust to be sure. That's fear. That's what good horror movies create.
The Exorcist has no jump scares, and yet it's regarded as one of the best horror films of all time. Why? Because what's scary isn't the BOOOGITY-BOO jump scares, but rather the idea that this kind of evil exists and can corrupt and possess an innocent child.
The Thing (1980) is a landmark horror film not because of the jump scares that it has (although those are exceptionally well executed), but because of AMAZING creature design work, and because the idea is freaking terrifying: someone who looks just like you, someone who seems perfectly normal, could be one of these otherworldly monsters. And that monster could escape and infect the entire planet and there would be almost nothing we could do to stop it.
Alien and Aliens feature jump scares, sure, but what's the scene everyone remembers? Right. The chestburster sequence. That's not a jump scare. It's just pure, otherworldly horror at this grotesque "birth" that has taken the life of the host. And the rest of the films are terrifying because you have no idea how to stop these monsters (other than taking off and nuking the site from orbit -- it's the only way to be sure). And, again, AMAZING creature design. The aliens are always juuuust barely visible, they blend into the background, and they come crawling -- skittering, really -- out of the walls for you...and you know what's waiting for you when they catch you.
The original Nightmare on Elm Street is utterly terrifying not because of the gruesome kills (although those are pretty freaky), but because the idea itself is terrifying: you can die in your sleep, and there's almost nothing you can do to stop it.
Effective, high quality horror isn't about jump scares, it's about scary ideas that stay with you long after the movie ends. Nobody remembers the body that falls from the rafters or the cat that jumps out from behind a trash can before Jason menaces the virginal heroine. People remember the fact that he's this unstoppable killer who just...keeps...coming.
So, yeah "It's just jump scares" is absolutely a fair criticism of a horror film. The best horror, in my opinion, is the stuff that's based on horrific ideas.