Brave, Opera, Vivaldi, Epic, Blisk, (and Edge?) can pool development resources. I dont think all the forks would have as much problem as people believe they would. A ton of webkit users switched to blink nearly overnight.
I think the bigger issue is chrome implementing an new web feature that blink-fork2 and firefox dont agree with, that web devs start implementing anyway. Google controls web development more than they control browser development.
Theres also the WideVine argument, but for me personally I dont see why i need my primary browser to also play netflix. Its not that hard to open a separate netflix app/browser. The amount of drm encapsulated video I watch in my browser is minimal to none.