It's been there for a while but it's done as an afterthought which can lead to cascading problems, and it isn't a great idea to use it. It stomps all over the distro's Python and is generally insecure, it's much safer to use the distro's own package managers.

I believe it came about to cater to Mac developers that don't want to bother with Linux based package managers, this becomes an easy out, but as mentioned previously, is more of an afterthought.