The snarky stuff is almost certainly people being funny, but maybe this does not translate very well depending on where you are from...?
And perhaps 19 months ago fatties were very fringe, and now they are everywhere. I live in the south island of New Zealand and just in my city I personally know about 10 people with fatbikes...
What does it matter anyway if a new sub is created - there appears to be an extraordinary number of bike type specific subs anyway.