Why do people still have hope in / clinge on Firefox when projects like Librewolf and Waterfox exists? Yes those are still dependent on Mozilla's upstream changes, but users not trusting them have still options.
Maybe they're being realistic about how long these projects could survive without Mozilla doing all the work upstream?
Same reason people want Chromium to stay around: their forks will collapse within months if the free work from upstream stops happening.
Brave, Vivaldi, Opera, Tor Browser, Librewolf, they're all little more than reconfigurations and reskins of Chromium when you look at the entire code base. Yes, the Brave as block engine and Operas power saving modes are non-trivial, but the engine they're built on is the size of an operating system.