I can also actually play the game if the game lets me trade for items that I want on my current character, too.
Right now I have zero interest in playing Druid. I had no interest in them in Diablo 2, none in WoW, and none in Diablo 4. I simply have no interest in the theme of the class.
So if I find a Druid item in Diablo 4 it will have zero value to me unless I can trade it.
Trading doesn’t let you skip out on gameplay given that you have to trade for items of roughly equal value. Unless you’re insanely good at convincing people to trade items for significantly less than they’re worth, you still have to farm items to be able to trade for the items you want.
People in Diablo 2 “actually play the game” a lot despite open trading.