But I do believe people want uBlock to intercept http requests before rendering the web page. And from my understanding this has always been supported in Firefox, but never in Chrome.
I have used Firefox forever, I never switched to Chrome as it knew it never was fully open-source. The point of open source is that you're able to build the thing from sources with the exact functionality as in binary file they release.
The web is extremly important for everyone, and it is important that we still build an open web for everyone. When people use projects like Chrome, they let Google decide the direction of the web, just like Microsoft did with IE.
That Firefox was sometimes slower than Chrome and sometimes lacked features has never been a big productivy hit for me. Neither has web pages that didn't work in Firefox. In the worst cases I just need to start Chromium. I lose max 1 minute. That is nothing to sacrifice for keeping the web open.
The webRequest API does allow to intercept and cancel HTTP requests, it has been part of Chrome extensions API since 2011.
That said, I'm not convinced by this flashmob against Chrome. I like Google direction and Google philosophy behind Chrome, including its position on adblockers. So I hardly have any reason to switch to Firefox. Chromium is open source, Firefox is financed by Google, so it's hard for me to be convinced that Chrome somehow is bad. Especially when Firefox makes one bad move after another bad move (integrating weird third-party services within Browser, like Pocket or VPN or whatever).
And, yeah, I don't care about my privacy that much, especially not on the level to actively fight for it. I care about security, and that's about it.