The current trend is that many gamblers play games from 3rd party providers although the game is not provably fair. No doubt that in house game with provably fair system has its own market and there are still many gamblers play such game. In this case, casino has their own target and budget. Maybe having games from 3rd party providers is easier than creating their own games as it may cost them some more money to develop the games.
But some people prefer them since they can verify how fair the game was, sometimes I am doubting about the third party providers since we don't know how really fair the game is especially with dice, slots and virtual sports. You will notice that most of the time you are losing which can happen in provably fair games but the difference is that you can verify it and accept that you are really unlucky.