There's actually a few reasons they did this. Their scheduling previously had leagues launching like early December so people could play with Holiday time. The one month bump and one week bump of whichever leagues it was kinda fucked all that up. So this way people who have time off can come and play in a 'fresh' league without a stagnant economy and low population. It does seem kind of self-harming, but I think it's more for the players who play big spurts during the holidays. The league itself is weirdly doing okay, not booming or anything, but at this point looking steadier than the previous two leagues. Retention sliiiightly better, but still no Harvest or Ritual.
These leagues actually could have some issues as in previous years when launch was week 1 or 2 of December they'd hit some bugs or balance issues and then GGG themselves would be on break for like 4 days with less than a ghost crew running it. One year was particularly bad but Chris basically said he's not going to force his server guys to leave their families to try and fuck with the server stuff without knowing 100% what the problem was ahead of time.
Overall buncha leagues that range from "nah" to "neat." Heist will be fun for about 10 hours, Delve may be better than last time, but still will suck, multi boss should be interesting but people will need bossing builds which usually clear like shit. Royales will be a flash in the pan per usual. Fun for a few hours maybe until the population logs off and never back on.