> Maybe someone can fork Firefox and make it run better, hard cap how much a browser window can use

Browsing web requires more and more RAM each year but I don't think browsers are the main reason - sites use more and more JS code. With a hard cap many sites will stop working. Software bloat is a natural tendency, the path of least resistance. Trimming weigh requires a significant effort and in case of web - a coordinated effort. I don't believe it could happen unless Google (having a browser with >60% market share) will force this but Google own sites are among worst offenders in term of hardware requirements.