So you're saying that being unable to prove the provenance of the image (whether it's original or not), becoming immediately exposed to downgrade attack, to someone injecting malware to /sys and you being unable to detect it.... That's not a big deal?
:)
Well, go for it, fork and "provide support" to the hardware hostile to non-stock OS, be a hero :)
hostile to non-stock OS - where are you getting this from?
If the bootloader cannot be unlocked, relocked, or doesn't provide timely updates to firmware/hardware, it's hostile.
The rest is not (might be lazy, insecure or just silly but not hostile)
It's surprising some vendors still don't support unlocking and/or relocking.