OLD took off when I was still pretty young (~20) so I might be talking out of my ass here and older people can correct me. I'll also preface this by saying the primary purpose of online dating for most people (in particular people on swipe apps) is casual sex. I know people can and do get into LTRs from it but I do not think that's the target audience.

One of the complaints I see about online dating is it drastically changed the dating field for the average man especially in regards to casual dating. Women suddenly had far more choice than they did previously and 80% of women were vying for the top 20% of men. My theory is that OLD did not change the game, it merely brought the wrong type of people into the casual dating scene.

Prior to Tinder and other swipe apps casual dating was for highly sociosexual people who liked to party. If you wanted to have NSA sex you actually had to go out and interact with people face to face. You needed to at least be an ambivert (if not outright extrovert) with medium to low inhibition. Swipe apps changed that. All of a sudden you could arrange an ONS without ever getting out of your bed. This enabled many people who would have never been in the casual SMP--introverts, socially anxious people, high inhib nerds--to suddenly enter it. But the qualities needed to be successful with casual dating did not change. Women who are into it casual sex are still high sociosexual, low inhib people who want high sociosexual, low inhib men. The men who do not have these qualities and are not successful in obtaining casual encounters online would not have been successful in the irl casual SMP either.

This reflects my anecdotal experience too. As I said Tinder/OLD wasn't mainstream when I started dating. The guys I saw racking up their N counts were rich frat brothers and bad boys i.e. the same type of guy you see being successful in online dating today. Average internet nerds were never good at obtaining NSA sex. They either didn't date or dated equally high inhib nerdy women. OLD did not change how casual dating functions and the people who complain about it are the type that wouldn't have been good at casual dating even without it.