To me it seems moot.
What's the secret to doing well in a racing game? Firstly you have to control your inputs to the game - turning the wheel at the right time, pressing the pedals at the right time, using them in a controlled manner.
Secondly, if the game is nominally a simulation, you usually need to create setups to get the absolute best times.
I think to do both of those things to a high standard you either really need to know what you're doing before you start or you really need data that this game doesn't really give you.
That to me is why it isn't a sim.
To me it's about a game that has a high skill ceiling. People seem to fret too much about the skill floor - whether that's "sim racers" fretting about how easy the cars are to crash or "game developers" who are worried whether the game is easy enough for so-called casual gamers.
It's about how can I see what others can do in the game, how can I compare that to what I can do in the game and say "I suck because..." and how I can create a path, a series of goals towards the top of the leaderboards - and this is the key thing - without going and playing a different game.
If I do that, then this game has failed. Of course, driving being what it is, once you've learnt in one game other games, even featureless ones, are probably easy to master.
You certainly won't learn to be skilled at playing/driving sims by playing this game will you? Not unless you do it accidentally.
Does that make it an arcade game? Probably not, because, as I say if you've played a good sim and perhaps managed to fathom setups and maybe had someone point out where you're slow and why you're slow (I suspect more often than not overdriving is the biggest cause. Which is a path to nowhere because the guy who thinks he's going absolutely as hard and fast as it is possible to go without crashing and his time is still 1 or 2 seconds off the top of the leaderboard will either try harder and harder to push and will never improve more than a tenth or so, or he'll start to crash and get slower. Slowing down to speed up doesn't compute - even though logically, if your time is 2 seconds slower you really shouldn't need to be driving every corner on the limit. It's self evident you're over driving if you find yourself fighting the car)
But then he decides that the difference must be setup. And that's a complete black box and unknown world that this game chooses to keep a mystery.
You cannot really see the aliens lap times, sector times, watch their lap in detail, save setups, exchange setups. There's no information at all about why you might want to change setup nor what you would change them to and what differences they would make if you did. There's no motec data or other telemetry as far as I can tell.
In that sense the game is a long way from being a sim, and I would argue it's a game that mostly fails people who haven't used sims before because no matter how easily someone can or cannot drive the cars in novice mode, anyone who bought this game hoping to learn to drive a sim is not going to be able to access 99% of what that really means.
If you think "Get real" means "oops, the car spins a bit more easily now", then sure, it's a sim, but that's not really what it should be about. It should be about why is my time on Bridge in the Saleen 1 second off the top placed guy? And how can I get faster?