Netlify is a company working hard to get lots of people locked into their companies ecosystem. This is a very bad thing for the open web.
The principles behind JAM are platform-agnostic though.
As I see it, Netlify is just dressing serverless in a new hat.
What are you implying?
That has a specific meaning whereby they prevent customers from leaving, somehow, but forcing everyone onto their platform.
As far as I can tell, the basis for this claim is that somehow the "jamstack" label is so valuable that people will be "forced" to work with Netlify so they can enjoy the privilege of using that trademarked term, but you'll forgive me if I find that to be a pretty weak basis upon which to levy such a strong claim.
Ultimately, again, this is just an architectural pattern and a bunch of open standards. Netlify is absolutely guilty of hyping the holy heck out of this thing as though it's the silver bullet that'll solve all of the world's problems. And sure, maybe they're trying to build a brand around it.
But I fail to see how any of this is so nefarious as to qualify as attempted "lock-in".
Even their serverless functions api and DB can be connected to any serverless provider.
But I admit that the hype will eventually die up and someone else would be able to trademark their model of simple stupid website publishing, hey I guess I should do just that. SSWP here we go!