> wouldn't it be best for the web/devs that they switched to chrome's engine?

Why would that be best? I don't think the problem with Firefox is the engine (anymore), I think it's the design choices Mozilla continues to make.

If Firefox switched to the chromium engine, then why would I bother to continue to use it? Surely it would be better to switch to one of the "privacy-oriented" Chromium-based browsers that have been around for a long time now.