Not only is accessibility important in and of itself, but starting with a clean, accessible base implies standardization and interop, and makes things a lot easier to automate and extend.

Things that challenge accessibility plugins challenge any plugins. Steps away from accessibility are always steps towards lock-in.

> The inherent fragmentation and HW compatibility issues are much more pertinent.

But you seem to desire this. Don't buy the wrong laptop if you like lock-in; Apple and MS aren't making their OS compatible with your every hardware whim. Or learn how to reverse-engineer and write drivers.