yes - maintaining all special cases is an effort.
yes, but your mileage may vary: You often have a special case where general performance measuerement didb't catch the use case.
yes - that are all people involde in debian or generally in Open Source.
yes, throwing out old clumsy code with special workaround for old hardware flaws is a great cleanup.
It seems you're talking about something different than what the discussion is about: this discussion is about the baselines for generated binaries. This isn't a discussion about dropping support for certain architectures and removing code.
I carefully asked what I asked because I'd like to see real data about what advantages there are to defaulting compiler flags to an x86-64 level other than default, for instance.
Answering "yes" without providing any information or links to information or measurements isn't really all that helpful.
Thanks, John Klos