The main thing is that Python is often in the top 10 choices for almost every problem on top of being insanely easy to learn and write; it also doesn't fragment its community - its standard library is so ridiculously large there are very few fault lines to break upon.

It's rarely the best choice, or even the fifth best. But if it's OK at a dozen things, then it makes it all but impossible to ignore. The fact that it sucks to write a GUI in is fine as long as I can put some basic "go" buttons and text boxes in front of a web scraper.