Hmm, I haven't been into webcomics in quite a few years. Offhand guesses...
My first and best guess is a different webhost. Webcomics have some oddly specific server issues, because people often come and binge large parts of their archives they need much larger monthly transfer allowances relative to their small amount of actual data*. This basically meant there were some pretty limited options we had for throwing up a webcomic because a lot of free server sites would just puke at seeing what could happen to an established comic, we referred to it as the popularity curse. You started your comic, got a few hundred readers, built your skills, then suddenly got a big break and recognized or recc'd by a big forum like RPG.NET, Something Awful, or Penny Arcade... and your service got smashed like an egg hit by a sledgehammer when twenty thousand new readers came to check it out. It was basically either DrunkDuck, Keenspace, or watch your project crash and burn right when it got popular and you suddenly got an influx of new readers binging your archives. Keenspace allowed Adult material but limited it pretty severely, DrunkDuck did not from what I recall.
It looks like both their successors do today, and now there's an abundance of other options, so it's simply easier to do. I would also suspect Patreon and the ease of getting a few dollars out of people for porn to be a factor.
*This isn't as true anymore as times have changed. A years' worth of webcomic used to be a huge amount of bandwidth, now not so much.