Sorry, I don't see much of a theory there either. Actually, I don't see anything much sensible - maybe it's an editing problem and the rest of the content, along with his "theory", is contained in the full article?
The discussion about the skill level of players doesn't have any merit in my eyes. Just like death and taxes, rake is the great leveller in poker.
Everybody pays it so the sites don't care if it's sharks or donkeys that are playing, as long as they're paying rake. The suggestion that multi-tabling is a bad thing in this context makes even less sense: surely the only thing better than a player paying rake to you is having them pay rake to you on six tables all at once.
If the suggestion is that the winning sharks are the ones most likely to have rakeback, and therefore the sites make less money off them than they do off the donkeys who don't have it then maybe we've got something to talk about.
A few thoughts though. First, do the figures actually support that? Rakeback is available to anyone who thinks to look for it before the sign up to a site, not just to sharks, and if anything it can encourage otherwise losing players (aka the "rakeback pros") to continue playing.
Second, how much money do you get per annum out of a shark with rakeback vs a donkey without? Obviously it'd vary from person to person, but I'd expect that the shark with rakeback is putting in a
lot more time at the tables and over a given period of time you'd still be making more money out of the shark than they donkey thanks to the volume they play - which is assisted by multi-tabling. The shark would only have to put in, what, x% more
hands (where x is the rakeback percentage they're getting) than the rakebackless donkey in order to deliver the same amount of income to the site?
There's no actual detail in the article to talk about but I'm having trouble even accepting the general concepts at this stage.