All true. We're all free to install any DE environment we want. But defaults are definitely useful to the entry level Linux users. I would love to see the day when the first (and easiest) choice for Joe Dad and Mary Mum setting up a computer for themselves and their kids is Linux with an easy to use DE instead of Win10/MacOS, with defaults that include LibreOffice instead of Pages/Office365, Firefox instead of Safari/Edge, and more.

Yes, many distros offer this out of the box right now, but it's not at the forefront of Joe-average's mind, because it's still not easy enough.

I just think that if there was less fragmentation (see my Linux Mint XEd example above), we could make much faster progress toward a FOSS world for the average user. Note, I'm talking about less fragmentation - not zero fragmentation.