I was suggestion official extensions, so you could not install or disable them, the reason I mentioned some could be put directly in the browser is if the same functionality can't be done by a pure extension or it would be much efficient directly in the browser.

I completely agree that you should be able to disable/unintall Mozilla extensions and replace them if you want with different ones(maybe you know of a better reader mode or a better ad blocker extension)

In fact this extension may not even be installed , just be part of Mozilla code base so any update will be reviewed