It is not a good business model for aquisition at all, from any point of view.
It does work for retention of good players though.
Players don’t need to be taught to make multiple signups. Anyone who knows how to turn a computer on can work out if they set up a different email address they can get a signup bonus again.
The multiple account abuses you object to are almost all in the CPA-gift sector.
Rakeback is all about retaining good players by giving them a share of the revenue they create for the site. I have rakeback on some of my poker accounts, and that means I stick around at those sites once I clear the signup bonus, instead of go and sign up at one of the dozen other sites that launched this month
Rakeback is EXACTLY what you do with your good players, only more formalised and fairer because it’s not just the squeaky wheels getting the grease.
Irrational opposition to rakeback from casino affiliates is hurting poker players and making it possible for shady characters (if any exist – I’ve never come accross any since it is better to keep 5% of a year of play than 25% of a month’s) to leave players high and dry.
If you really cared about the players, you would be trying to make rakeback an established part of the poker industry. That way, no one would be getting ripped off.
Also, how is being left high and dry by an empty rakeback promise different from signing up through a non rakeback link? In both cases, the player gets nothing.