Hi there, i know photoshop (or elements) is powerful and useful, but any reasons why the corel imaging softwares (paint shop, photoimpact) are not as popular?

are there less features? lousier UI? more expensive? not as available? not much professional support?

just wondering, because i was surfing some reviews on the corel products and looking through their features and UI, seems pretty nifty!!
not much discussion on clubsnap as well, so i assume the userbase is really small.