that's why they've killed XUL. that's why they're going even further by enforcing an inferior extension standard from their supposed competitor. that's why they've killed off the extensions and about:config for the android version. that's why you can't even use a private extension on desktop without jumping through the hoops. that's why usercss (toolkit.legacyUserProfileCustomizations.stylesheets - legacy and disabled by default - the writing is on the wall already) and userjs will get axed. that's why about:config will get axed on the desktop version as well.
all of that is just off the top of my head. and in the end, Firefox will be a clunky and inferior alternative for Chrome with not 2%, but 0.2% of the market. which is the goal.