Not to be pedantic, but it looks to me like they are both talking about the same thing. The GP sounds like he is missing things in Cinnamon that are taken for granted in modern DE's, that it is simple and at the level that modern DE's were when they were less mature.

One might say that Windows 98 is "less mature" than today's OS's, and if Cinnamon has features comparable to Windows 98, one might think of it being less mature as well.