This seems to scream "separate me!". Why is it acceptable to put all this responsibility into one giant ugly ball? We desperately need separate layout engines, parsers, renderers, etc. Assemble-your-own-browser.
What tangible advantage would this have? Having competing browsers seems possible, but since end-users wouldn't be choosing individual browser components anyway, it wouldn't actually improve anything.
Choice matters. Sometimes you have to make a choice on behalf of your users. I think that’s what the industry as a whole has done here. Nothing is preventing people from rolling their own modular web browser. Maybe things like Beaker Browser and TOR Browser are versions of that same idea but approached from a specific use case.
Thanks for this comment. I think your idea is good but not for the same reasons that a web browser suite is a good idea for most non-technical users.