There may be other technical solutions that are better from a technology POV.
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.
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.