If you did not know, the Missouri casinos cannot bar a skilled blackjack player from playing. I was around when the state put a vote to allow casinos and blackjack in the early 1990s. One of the stipulations the casinos made to convince the public was that blackjack was a game of skill. Of course they can apply countermeasures- but these need to be applied to the whole table.
Ameristar STL. I played the 6 deck hoping I could fly under the radar. I tried the 6 deck, I moved to the high limit dd knowing countermeasures would come on the next shuffle. The table was filled with 3 other good patrons. Dealer instantly went from 75% pen to "12 cards (11% pen). The patrons didn't like the looks of this change and cashed out and fled faster than Ryan Lochte out of Brazil. I have seen it happen before.
Does this make good business sense? If I were shareholder, I would say no. The regular players would probably not notice if they reduced pen to 40, 50,or 60% or if the table limit was lowered. The other players probably would not notice. But players can sense something is up and don't like it when they suddenly switch to one round and shuffle. So why mess with one player that might visit 2 or 3 times a year for a few hours and risk sending some of your good customers out the door and maybe to one of the competitors?