The race to replace Redis

Corporate lawyers are in the business of aggressively trying to make you give away all your rights to them. There's something of a licensing Overton window (let's define upper licenses as more copyleft and lower as more permissive). They will always try to convince you the upper side of the window is toxic poison to shift the window downwards. Once they successful convince everyone the AGPL is pure poison they'll move on to the GPL and then the LGPL, and then MIT and convince you to public-domain everything, and if they somehow manage to succeed at that, they'll try to convince you public domain is bad and you should assign your copyright to *their company* for safekeeping.

They've already succeeded to a moderate extent if you've noticed the large number of developers who don't like the GPL.

The fact that corporate lawyers don't like something tells you more about the corporation than about the something.

The legal definition of "derivative work" is not obvious, but we should probably act as if it's on our side. That's what corporate lawyers do - act as if it's on their side and try to convince everyone it's on their side - and it often works for them. They've succeeded in convincing a lot of developers that some technical step in the creation of software (such as linking) is what creates a derivative work and thereby made a lot of people pre-emptively give up on derivative work infringement "cases" that might have actually been enforceable.

If there's any ambiguity as to whether your work is derivative of a corporation's, you better believe that corporation is going to sue you and find out what the judge thinks, not just shrug its shoulders and say the definition of a derivative work is ambiguous. Free software has to be pursued with the same zealotry, not every single time, but at least enough times that corporations are scared it could happen and don't do it, just like we're usually scared of them.

Otherwise the corporate lawyers win by default.