Turn signal thought process

I’m in Minneapolis/St Paul area. I see this all the time, people slowing down to take a turn and at the absolute last moment they put on their blinker so it doesn’t help anything. The people waiting cannot go, the cars behind them have no time to slow up and create a little space. Even when there’s a turn lane they cut over into the turn lane and use the blinker at the last second. Can anyone explain the thought process here? Why not just skip the blinker altogether?