I honestly don't remember what the last time was Chrome introduced some cool new feature in Chrome. Maybe the PDF reader?

PWA, WebComponents, File Access, Worklets and Houdini and everything else in HTML5/CSS3 still missing from ChromeOS are all being pushed by Chrome.

I don't see how those really benefit the end user.

Firefox has developed Container Tabs, First Party Isolation, integrated Tracking Blocker, an early alpha for a password manager, Screenshots, Firefox Sync, DNS over HTTP and eSNI, not to mention that Mozilla lets addons do much more with the browser so an addon can really change how your browser works instead of being severely limited in what it can do.

Firebug was probably the only add-on I ever cared.

For everything else there are network protocols, native apps and scripting.

Blocking ads, should be done at the network layer.

Blocking ads can be done both on app and net layers. I use both piHole and uMatrix (and uBlock Origin on the phone), piHole eliminates the worst offenders already and the addons can make more direct modifications to traffic.

i'm a developer and i find it hard to give a shit about any of that, container tabs are cute but they end up breaking a lot of websites, the rest is not even a blip on my radar

as for addons changing how my browser works - no thanks, i'd rather have a consistently nice browser experience than have to re-install addons everywhere

If container tabs break your website, I suspect you're doing something shady with tracking. It does literally nothing but isolate cookies/storage/scripts.

Aside from File Access, I haven't seen any of these. PWA is sometimes mentioned on HN but I've never seen one in the wild (I had to look up the term a few weeks ago). Worklets, WebComponents, and Houdini, I never heard of. I'm not the most in the loop person since I'm not a web developer, but you'd think the cool stuff gets at least mentioned, so going with that, the most recent progressive feature that comes to mind is still the PDF reader (other than general maintenance work to keep up with HTML5, which all browsers do, and which I assume MSIE was also doing in the 4 year period mentioned -- or CSS3 or whatever was hot back then).

Twitter and Starbucks mobile apps are PWAs.

Houdini allows for low level control of CSS rendering, basically it allows for creating CSS classes with our own paint methods, and in the process having lower level JavaScript concurrency using less resources than workers.