Many tabletop game designers think that they are very simple, therefore not requiring any new player introductions as most of the players would have played it before in real life.
But this view was incredibly wrong.
There are many local variations in rulesets for tabletop games. For example, mahjong from different areas may have different rules for 'pongs','gongs' or winning. If an international mahjong player wanted to try out blood mahjong, it would be very difficult for the player to find out the rules for himself without the help of new player introductions.
There was also another group of players who rarely have the chance of playing tabletop games, would even fail at playing Dou Dizhu, and despite that they still want to improve their skills. It wouldn't cost them much to play these tabletop games once in a while, and would also hope they can get some newbie tips when they play.