"The kernel can be changed freely without worrying about supporting drivers that cannot be updated because they only exist as binaries."

Nice theory. It is just, that writing drivers is hard and not many people are capable of it. So for most existing driver issues, it will be much cheaper to buy new expensive hardware that might actually be somewhat supported for a while - than hiring someone to write a reliable open-source driver for it. (oh and of course, you also cannot buy the latest hardware as then there is mostly no support there yet)

I would love my whole system to be fully open source and working.

But since hardware is very closed anyway, I would rather have a couple more binary blobs on my system, that work reliable - instead of a bunch of open, but very faulty drivers. So I very much would prefer a stable Linux ABI.

Because without - I am forced to use Windows on my new Laptop, as everything runs much slower and buggier on linux - and I would like to use my laptop to work on other things - and not on the laptop itself.