It really has very little to do with men "being owed sex" by women. Most men don't really believe they're owed sex by women, or anyone for that matter. The big issue is that society has placed such an emphasis on premarital sex and random hookups and casual sex that young men are beginning to feel like if they aren't having sex they are missing out on an integral part of life, which is not the case.
Sure, there are definitely men out there who truly believe that women are simply there to please them and be their slaves, but that is not the case for the vast majority of men, even so-called incels. They have simply been led to believe that sex is an amazing, huge part of life, that it is integral to a normal life and, while it is important to a healthy relationship, it's not necessary to live a normal life.
It also comes back, in a way, to the destruction of traditional masculinity. If they can convince millions of men that sex is the only thing that matters, that it is the most important part of a relationship and of life, then that's all they're going to care about. They're not going to focus on other things such as learning new skills or trade or bettering themselves in some other way.
Of course, the funny part of all this is that by convincing men that sex is the only thing that matters, they are completely reducing women to only being important in a sexual way. Although, I suppose that's part of the plan too. After all, we can't have women being motherly figures or caring individuals in a household or in life in general. We have to have them choose careers that debase them and destroy their mental well-being. It really is all connected I guess. The destruction of the family unit, the destruction of traditional masculinity, the destruction of traditional femininity, the sexualization of children... It really does circle back to the destruction of traditional values in a way that lets them swoop in and replace traditional morality with some sort of perverted new age "progressive" morality.
Anyway, that's my $0.02
What you talk about is part of the problem, but the main way hookup culture creates incels is by giving women a grossly overinflated perception of their SMV. What happens is that Chad is willing to choose an average woman for a one night stand rather than go through a dry spell when he can't find a woman at his SMV level. This gives these women the impression that they have a chance at locking a Chad into an LTR when they don't. But they feel entitled to a Chad and consider men at their own SMV level subhuman. So they spend their best years riding the cock carousel hoping to land that Chad and refusing to accept a more realistic option. The Manosphere calls these women 49ers (4s who feel entitled to a 9). Meanwhile men outside the Chad zone have to dumpster dive to even have a chance, and a mix of disgust and pure numbers (60% of men get left out even if all the bottom 20% women pair up with bottom 80% men) means that a large number of men are locked out of the sexual market completely.
Prior to hookup culture it was different. Premarital sex wasn't an option so the Chads couldn't cycle through 80% of the women. They quickly paired up with the highest SMV women, so women lower on the SMV totem pole had a realistic idea early on of what their options were. They didn't spend 20 years Chad chasing because the Chads were off the market by the end of high school. So average men had a chance with women at their level and incels didn't exist in significant numbers.