But people that work on FOSS, as owners of the IP they create, are also allowed to put whatever restrictions they want on it; if you don't like those restrictions, don't use it. Pretty simple.
Sure. The question is - do they still get to claim the "FOSS" moral high ground and branding, once they've "put whatever restrictions they want on it".
I think a _lot_ of people say "No" to that question. Are Redis/Mongo et al "Free Open Source Software"? I tend to think not. I'm completely behind their right to change the license freedoms they choose to grant.
But at least in my opinion, it's no longer "free open source software".
It's quite clearly not rms's definition of free software. It's less free than the EFF's definition of gpl (in any of its versions). It's almost certainly not what ESR means by "Open Source".
I don't know who gets to say what is and isn't "FOSS", but I'd suggest all three of those have at the very least "prior art" ownership of the definition, and the Mongo/Redis clearly do not have any standing to define that term...