When you guys say "divebombed," do you mean outbraked you on the inside, or something else?
I'm thinking this. It's a legitimate move that you see in things like F1. You CAN muscle your car into a position, especially if you're up along side beforehand in which case it's absolutely a legit move and the passed car should leave room, but equally the passing car should leave room as much as they can, but even in F1 the passing car, once more than half way past, can edge them out near the edge of the track with no repurcussions.
I think the problem with GT Sport and people complaining about the penalties is that people don't understand the generally agreed rules of passing in real motorsport and think far too many moves are immediately illegal. Equally others assume weaving in from of someone trying to pass you who has the speed is a legit defending move when it's not. One significant change in direction then you have to give it up!
I do think the GT Sport mode needs a full tutorial covering all of this. What's acceptable and what isn't and give you missions that educate you by actually doing it. These flimsy videos you have to watch cover about 5% of what needs to be told to players.
I know for me personally I've had some dirty moves on me, and some misjudged moves. The dirty moves need penalised, then misjudged moves often need penalised but to a lesser degree than we see, and then game needs to take into account what's up ahead of every driver when taking into account. There's many incidents where someone edges a car off the road, the fly back onto the track and you crash into them and then you get penalised for bashing into them, or you avoid the collision ahead but create another of your own where someone else suffers and you get a penalty. Needs a complex AI to even begin to judge these situations appropriately.