OK, but surely it should at least isolate buggy extensions so they can't compromise the browser itself? Wasn't better security and stability in the presence of bad extensions a key selling point of the new extension model? In practice, Firefox was failing to shut down and restart cleanly for me perhaps one time in three since Quantum, having been solid as a rock until that point. (I say "was" because I haven't yet seen this problem since updating to 59 the other day, so it's possible that that particular bug has now been fixed.)

Likewise, if it makes better extensions possible, how come the only observable difference so far seems to be that various things that extensions used to be able to do are no longer possible? It's looking like a classic case of going all-in on a big software rewrite, but finding that a lot of little details have been overlooked and useful functionality has been lost as a result.