Whether any others have been made before now is anyone's guess. Botting is a known problem in online poker. If there's a golden goose out there, I'm sure it's being kept under wraps.
Most of their income does come from the weaker players at the table, but many of these bots were good enough to breakeven or do slightly better against the pros at the table too.
Strategic play, card counting, etc. A handful of heuristics make you an above average player and will get you thrown out of a casino. They'd be trivial to program.
I guess all that is novel here is a bot learned these techniques on its own.
I'm not sure what sort of "standard well-established techniques" that "would be trivial to program" you're talking about. Optimal play in no-limit hold'em is a tremendously complicated mixed strategy with a massive decision tree. To make things even more interesting, in almost any given situation there will be multiple "correct" plays that, to avoid being exploitable, should each be made some percentage of the time at random.
This AI is novel because it achieved a result that (as far as anybody knows) has never been achieved before, not because it figured out how to do something on its own.