Most men don't require the same emotional depth that women do, for sex to feel satisfying to them. This is common knowledge.
Emotional depth takes time to develop for most people. It's not something you typically cultivate in a one-night stand, for instance (though some people apparently can pull it off - it is somewhat rare, and even rarer for two people like this to encounter one another). This is common sense.
Thus women would have better and more satisfying sex if they took more time to actually build emotional intimacy with a man, before sleeping with him. During this process, most men would likely develop greater emotional depth and empathy for the woman they'll eventually have sex with... thus making the sex more satisfying for the woman. This process has the extra benefit of also filtering out many of the men who lack the patience or goodwill to actually build a relationship - the 'players'.
I don't think this is difficult to understand. However, from what I've seen/heard - this is frequently the root cause of unsatisfying sex for women. Frequently, not always - because it's not a direct/linear relationship between the two variables. Psychopaths for instance have 0 emotional depth, but are good at faking it, and reportedly often have great sex (I wouldn't know from personal experience - only from anecdotes I've heard). This 'enjoyment' however only lasts as long as they have a use for you. I am not recommending that you start having sex with psychopaths just because there's some skint anecdotal evidence that they're 'good in bed'.
If you have sex with a man 'too early', then you do not give him much incentive from thereon to develop greater emotional connection with you, and if that is the precedent upon which you founded your 'relationship', that's going to be difficult to overturn later. If you had sex with him too easy/early, and then you try to pull back and make it harder for him, it'll just look like you're playing games. It'll probably just p/ss him off, and rightly so.
Edit: I'll add to that, that reportedly many women (younger especially) have sex 'too soon' because they feel somehow pressured into it, or are anxious to please the guy whom they're attracted to. This is an error. Much like how women can sense simps and 'nice guys', men can also sense when a woman with low self-esteem is lowering her standards to try and please him - and it's not attractive.