Well, yeah, but they're not remotely near the first or only studio to do that. Every studio is developing cinematic universes these days, so to single out Universal for that is rather arbitrary.
It's the internet. People whine about things in an arbitrary way.
Especially since Universal invented the shared cinematic universe with Frankenstein Meets the Wolf Man in 1943. They were doing it 65 years before Marvel.
Sorry. I don't buy it. Universal monster mashups were a marketing gimmick improvised out of thin air. Continuity from movie to movie was slim to none. The MCU was architected as a large coherent tapestry to cover tentpole releases several years downstream.

Doing films this way has no real precedent. The closest I could think of was George Lucas' long-range Star Wars strategy but that didn't have the same level of corporate buy-in. Maybe another would be Disney's ongoing tradition of adapting (and coopting) classic fairy-tales. But we're in this era where everything is sort of engineered and field-tested to the point where the board votes and billions of dollars of capital are earmarked for back-to-back popcorn movies. There's never been a time where so much resources and commitment is being focused like this. Of course, the downside is if the direction goes off the rails (as it did with DC or the Josh Trank Fantastic 4) then you're stuck with what you just laid down as canon.