That's really gross. I guess then everyone thinks they need to use it because all these startups use it, but it's really just a simple notepad app with many alternatives.
I'm really happy I got our company out from using Notion. We just do markdown in Linear, which you can copy and paste from an editor easily.
It's really just standard "voluntary lock-in": any knowledge system you decide to use locks you into that knowledge system simply because you're going to be generating tons of content in it, which may at some point need to be migrated, and the longer you use it the more of a hassle that'll be.
And if it feels a bit gross (it's not, really, it's just what happens when someone has a good sales pitch) they're not holding your content hostage like some other platforms *cough*zendesk*cough*.