Earlier quoted context omitted.
It's also still considered one of the main-reasons for Chrome eating up all market share, that they now have the leading mobile OS under their control. You can invest a lot of money trying to remedy that, before it's actually a waste of money. And a lot of technologies and standards that were developed as part of Firefox OS still are very much around today. In terms of standards, they did a lot of work for camera and…
I thought the reasons that they lost market share was that they started cloning the chrome interface stripping out usable features (i.e. status bar) at the expense of fixing memory and performance issues. I stopped using Firefox when they removed the status bar and made it an extension and then went and bundled in a read later service extension.
And no, these UI changes were not made at the expense of fixing memory and performance issues.
The reason why they didn't fix those memory and performance issues, is because it would have required introducing the (now introduced) multiprocess architecture.
That would have required breaking all extensions (which is now being done with Firefox 57, along with breaking them to switch to a new extension API). So, that would have pissed off power users even more.
And also just in general, you have to understand that power users are not that important for market share. They make up maybe 1%. If they bring their friends and family all along, then maybe 15%.
There's a big number of users that are able to choose their own browser, but are not power users by any means. For example, around 40% of Firefox users don't have any extensions installed [1].
[1] The figure is from Sep 2015, but I don't think things have changed much since then. And if anything, the trend has so far been for this number to increase. https://bugzilla.mozilla.org/show_bug.cgi?id=1229949