1) That is precisely my point. End-users often think that new stuff can be easily added on top of older stuff, and if developers don't do that, they are just stupid, shortsighted, or whatever. For 2.10, we had to finish the GEGL port to give people much anticipated things like high bit depth precision editing (up to 32f per channel). For 3.0, we now have to port GIMP to an actually maintained version of GTK because some things are just broken for good in GTK2, this is mostly done and will be polished in the 2.99.x series. Once it's done, we will have the solid foundations to expose non-destructive editing (unless someone really clever arrives to hack it into v3.0 but I wouldn't hold my breath for that).

2) I'm the guy who wrote a chunk of that release notes (and most of the release notes in the past 10+ years). You don't need to babytalk to me about any of that stuff :)