I know Firefox is late to the game with this feature, but its really useful. For me, im using it to keep a number of tabgroups always open for different aws accounts.
It brings some order to things. Before tab groups, I was having lots of container tabs mixed in with ordinary tabs all over the place and often lost track of what was where.
And its the only browser that has container tabs with tab groups. In chrome, you still share cookies across all tab groups.
I still think its the best browser, at least for my needs.
One of the earliest user requests after Mozilla opened them up to the public!
They also track the other popular user requests, although it’s a total crapshoot weather they will ever get implemented. Moneymakers (AI features, Ad telemetry, shopping Sidebar, profitable search engine partnerships) tend to get pushed to the front of the pack.