Chrome was a new project, and didn't have to deal with the legacy of being built on top of the same source code as Netscape Navigator. I do not understand why you are trying to make this out to bash Firefox like they aren't as competent by taking ~10 years to implement multi-process browsing after Chrome. Legacy software and patterns are truly painstaking processes to iterate on.

But yes Electrolysis is the initiative that you should have referred to in the original comment.