Again, real racers have spotters and much better mirrors and generally much more feedback as to what is happening on the track. They can do things on track and and still race side by side, that we cannot. And they are professionals, not guys sitting on their couch with a $40 piece of plastic in their hand trying to negotiate their way around a race track.
Point being, sure, in real life you can dive under someone, outbrake them, nudge them, move them around a bit, it's all good. But this isn't real life, it's a video game, with limited vision, limited feedback as to what's happening all around you. As such, you need a much stricter set of rules, otherwise what you get is race 3 from Grand Valley East Reverse, a crash fest where guys who if you asked would say they were outbraking, but in reality they were divebombing, using other cars as brakes and guardrails, and ruining everyone else's enjoyment of their race, in pursuit of the lofty goal of winning a virtual race.
If your objective is to outbrake guys in the GT86 or any other car, from 30 feet back, then you're probably going to be disappointed by the infractions you pile up at Tsukuba and most other tracks. The rules of this series, as I understand them, require you to gain some speed in the draft to attempt a pass, outcorner someone to get a good run into the next corner and some draft assistance to get by, or to pressure someone into a mistake and slide by. You can also utilize a tire wear strategy, pit strategy and a team strategy. Seems to me like plenty of tools available for racecraft and whoever capitalizes on them, will do well. Whoever chooses to play by their own rules, will probably not be very happy after a race or two and maybe be looking for somewhere else to ply their trade.