Quite. On the other hand, it's not uncommon for non-x86 devices to be locked already, and unlockable ones are still the exception. The most popular phone and tablet in the world are not only locked, but controlled by a vendor that actively tries to re-lock devices that are unlocked.
On ARM it's almost always been the case that installing Linux has involved fiddling at least and outright cracking at most. MS legislating that one can't allow the bootloader to be unlocked makes no difference if the vendors don't currently allow that anyway.
The important use case here remains "putting a CD into an x86 system", because those are the only ones where a) Microsoft has a monopoly and b) installing Linux is never more complicated than sticking a CD in the tray and rebooting.