This change has basically no effect for anyone on a free workspace. Since you can’t read those messages anyway. It only matters if you were going to go paid.
I think it’s more likely that slack has decided that all free workspaces that would upgrade, probably have, and they don’t want to store all those messages that aren’t going to be read anyway.
The only time I actually experienced this was in the states. Lady doing 5 under in outside lane, big queue trying to get past by pulling in Infront of me (with space.) Had to push past my Britishness to undertake.