(I'm paranoid and FUDing because I care: there's some UX low hanging fruit before they could get rid of userChrome.css. For instance, you need userChrome.css to autohide the toolbar in full screen mode on macOS — that's not even a customization, it's a missing feature.)
For what it's worth, this change happened because people were seeing the stat() call involved in startup profiles, taking sufficient time that it seemed worthwhile to avoid it if possible, as far as I can tell.
Yes, there are. They are not a niche cohort.
EDIT: In fact, we have many more users with magnetic HDDs than who use userChrome.css. That tells you everything you need to know about this decision right there.
C'mon the directory structure would be cached already, even if it was not - the seek times for HDD are 3-4ms.
If your HDD has a seek time of 3-4ms on average, that means it needs to rotate completely in at most 6-8ms, which gives you a rotation speed of 7500-10,000 rpm. HDDs in data centers do that, sure. Consumer HDDs just don't do that, last I checked; they're mostly in the 5400-7200 rpm range, with laptops firmly in the 5400 bucket. See https://www.dell.com/en-us/shop/dell-laptops/sc/laptops?appl... for example (currently offered Dell laptops "for home" with an HDD: they're all 5400rpm). At 5400 rpm, your average latency from just the rotation is 5.5ms and your worst-case latency from the rotation is 11ms. That doesn't include other latency sources, but let's assume those are somehow scheduled away to happen during the rotation.
Keep in mind that what typically sticks in users' minds is worst-case, not average-case, behavior, so you have to bring your worst-case time budget down to whatever your target is.
You can still install Tridactyl in a normal installation of Firefox by following the instructions on our readme [1]. Admittedly, that may cease to be the case if Mozilla ever tire of us; people in locked-down corporate environments would then find it hard or impossible to install Tridactyl but we'd make it as easy as possible for everyone else.
On topic, I'd argue that Mozilla are just desperately trying to cling on to ordinary users; the "war" against power users is a war of (totally understandable) neglect rather than spite.
[1]: https://github.com/tridactyl/tridactyl/blob/master/readme.md
There was some of the same phenomenon with Google, but the real difference is that Google pushed Chrome very strongly on the biggest web properties in the world, had it packaged in some other software installers, and advertised it. That's why Chrome has the market-share it does today.
Mozilla appears to now be courting the ordinary user market without having either the passion of power users driving it, or the world's biggest web properties shilling it.
To this day, visiting google.com (#1 website) in my default browser pops up a large notification informing me I need to switch to Chrome to 'hide annoying ads and protect against malware on the web.' Visting YouTube.com (#2 website) pops up a slightly less annoying notification on the bottom that says "Google recommends using Chrome, a fast and secure browser."
I haven't been able to figure out for years now how they think this is going to work. Ordinary users are going to do what their IT administrator/IT friend says, use the OS default, or use products recommended by massive marketing campaigns.
Just about every person I know that uses or used to use Firefox does so because I told them to use it or (more likely) I installed it for them. That's how most people start using Firefox.
> On topic, I'd argue that Mozilla are just desperately trying to cling on to ordinary users; the "war" against power users is a war of (totally understandable) neglect rather than spite.
Perhaps, but meanwhile, as we muse about Tridactyl and the abandonment of userChrome and userContent, a thread about the possibility of Firefox removing webRequest in the future rises to #2. It's getting harder to justify Firefox and Mozilla by the moment.