Yea, after i saw my damage on last race i started thinking about it too..
The way i see it, no one here, if gets choosed to be driver irl, will drive like it's driving right now, jumping, sliding and using all kerbs, because that would have a great negative impact on the car (fixing and re-doing all the work would cost the team their weekend for example).
This is a simulator though, which is basicly a game, so you have to remember that some things aren't simulated the way they should (i totally agree, irl if we cut the bl1 t1's chicane we would probably wreck the car's suspesion), but this isn't real life, so we can abuse a little more, and give more of ourselfes.
But i don't understand what you mean by unrealistic times.. it's not like a BF1 is pushing the FBM to make those times, it's just the way to go faster, without cheating. If in hotlap mode the lap is valid (1'12.08 is pretty alien-like), then i don't see how 1'12 mid/high pace isn't something normal.
Also, there are quite a few doing them, and almost everyone i saw in V1 used those kerbs and others.