What WP did right is to choose a platform supported EVERYWHERE (PHP, and not Ruby, Java or other crap only supported by few hosters), with a shitload of developers (again, the massive advantage of PHP), and packed the installation process in a way everyone from an 8-year old school kid to a 70-year old grandpa can handle (and literally, I have seen both!).
Also add in that wordpress.com's free hosting platform... well... surpasses any other blog solution by far.
Are you sure? To me, it's by far the slowest one of them all.
When WP was created, their options were PHP or Perl. PHP was by far the hottest thing back then, so what they actually did was use the hot tech of the day and made it work. The reason PHP is supported everywhere is for the same reason; back then it was PHP or Perl via CGI. Python was added later and was also supported EVERYWHERE.
Germanys big hosting player Strato doesn't offer Python in its cheap plans, Hosteurope according to their FAQ is stuck at python 2.6.
Granted, a German-centered POV, but still. Python support is far from mainstream.
It's full of horrendous things all the way down, but it just doesn't matter.