One piece in that blog that caught my eye is where the blogger references the roll20 stats for Q4 2021 to point out 4e was being more widely played on the platform than Numenara, 13th Age, and various other systems as a means of pumping 4e's success.
While I'm not sure how well set up roll20 is for handling non-5e games in general (though I do know trying to play modified 1e on it is a struggle), I'd posit it's well suited for 4e's sometimes-complex grid-based game and thus would be attracitve to 4e DMs and players; and that in any case this amounts to comparing the size of one grain of sand vs another when both sit next to a boulder.