That isn’t the only factor though. Take OnePlus, for example. You can still unlock their bootloaders, but if you check out XDA you’ll see that their hasn’t been any custom roms for a OnePlus flagship since the 9 pro because they stopped publishing the MSM tool, so the risk of bricking the phone is too great.
Not it isn’t. Plenty of OEMs let you unlock the bootloader.
That isn’t the only factor though. Take OnePlus, for example. You can still unlock their bootloaders, but if you check out XDA you’ll see that their hasn’t been any custom roms for a OnePlus flagship since the 9 pro because they stopped publishing the MSM tool, so the risk of bricking the phone is too great.
I guess the same thing is happened with samsung after the s10 series. No new roms for the newer ones apart from 1 or 2 oneui based roms.