Modern hobbyist boardgames can be quite complex. They also come with a ton of components: cards, different kind of tokens, miniatures and cards among other things.
The games also run for several hours and once setup it makes sense to play the same game a few times in a row as the setup times can be quite long. Even playing for the whole weekend there isn't that much time to go through several games. For example this weekend we prepared by "only" bringing five big boz games with us (plus a few lighter games to play in between those long games). In just those five games there must be thousands of game pieces.
With sll the pieces also come various symbols and keywords. Each one of those with their own distinct rules or abilities that need to be remembered. While many of the pieces are different enough between games there is only so many different ways to visualize simple enough those things that after s few games they seriously start to mix up, everyone remembering different variation of all the previous games.