Besides the ability to replay games and learn, as previously mentioned, hiding your history helps those who cheat.
There have been a few times when someone does a suspicious play that doesn't help themselves and gives the lead to another player. It's nice to be able to glance at their friends list, and if they are friends and play a lot together, at least I can write a note that they are probably cheating and avoid them. Sometimes, their history gives them away on other ways too.
If all their info is hidden, then cheating is much harder to detect.
There have been a few times when someone does a suspicious play that doesn't help themselves and gives the lead to another player. It's nice to be able to glance at their friends list, and if they are friends and play a lot together, at least I can write a note that they are probably cheating and avoid them. Sometimes, their history gives them away on other ways too.
If all their info is hidden, then cheating is much harder to detect.