People love their history. That's why sometimes they try to make something like Ruby on Rails but on PHP or something else. Examples: Symphony, PHP on Rails.
I think that the spirit of pioneer is very important.
Ruby on Rails is:
fast;
flexible;
beautiful (i don't mean textmate or mac :-);
original.. as Mohamed Ali.
and no one can beat it.
PHP is good only if you want to make static html site.