LMAO Sim!
The main problem in the market isn't one of abilities of developers, but of rights. We'd no doubt still have a GPx-style sim of note if FOM and/or the FIA weren't so closed-minded money-grabbers.
That's not to everyone's taste, but it is to the taste of the masses who've been left with not a lot since F1C and GP4's demise.
LFS's good, but it's hardly hardcore in the same way iRacing is. rFactor's got it's lovers and haters, and almost too many mods to choose from. There's things like GTR and GT Legends, which never took off beyond a few months of interest for most it seems - GT Legends suffered the same as GPL, in that it just didn't have mass-appeal, no matter how good it is. iRacing, while probably being the best all-rounder in terms of realism, is poorly set-out financially and doesn't have anything in the way of a top-level car. It's also far too structured at the moment, being everything a community isn't, but hopefully that will change and they'll allow private league races.
It's a niche market all right, but the choice for you is out there if you look for it. Personally, I'm quite happy sticking to GPL and NR2003/GTP until I decide whether I can get into iRacing enough to subscribe permanently. rFactor's never done it for me, and LFS was nothing but a bit of fun. I realised how crap modern F1 sims were when I got into GPL, so they've never interested me since anyway.
Racing against the AI is dead. Accept it. Online is all that matters.