I honestly can't remember the last time I've seen a PI flag picked up or not thrown because of the uncatchable rule. I've only seen refs throwing flags everytime there's the slightest bit of contact regardless of where the ball is. Then you hear commentators go 'well they could say it's uncatchable but if there is no contact maybe the pass wouldn't look so uncatchable'. Maybe it's just me but after some of PI I've seen, those calls did not strike me in any way.