I'm not sure there are many socially acceptable places remaining for finding dates post-college, outside of the bar scene and singles' groups. It's fine if you organically join an activity meetup and happen to connect with people there, but if you go to these groups just to hit on people, you'd get in trouble pretty quick -- especially if you are not very physically attractive or socially skilled/charming.
The dating apps provide a safe place for people to look for dates, mutually, and at least provides a pre-filter to exclude anyone that seems red-flaggy right off the bat. It's not the worst way to meet people or practice social skills, really. Expensive though, especially if you frequently buy dinner or drinks.
I've used OkCupid on and off for ten years (or maybe a bit longer), starting from when I was young and super socially awkward, through the somewhat more grown-up years, to the boring old version of myself now (with a stable, long-term relationship that also started on OkCupid). A few summer flings, a few on-and-offs, many 1-date-only experiences... but overall, I met a lot of really fantastic people that way (including many that became friends; we just weren't compatible romantically/sexually/emotionally). Never had a bad experience.
I'm a straight man in my 30s, mostly cis, average height/weight, average attractiveness. That is to say I have no special superpowers, but I also didn't have any huge barriers except my own awkwardness. Forcing myself to spend time on the dating apps and meeting people (alongside other social activities) really helped to get me out of my shell and learn to be OK with myself.
Another foundational thing to being an adult, IMO, is giving yourself the room to fuck up and be forgiven later... not so much "fake it till you make it" but "keep doing it and just make sure to learn from your failures" -- implying a certain level of authentic vulnerability, not just false bravado and shallow suave.
And also, learning to enjoy the company of others on many different levels: not just romantically or professionally, but also recreationally, emotionally, intellectually, etc. Mixing dating apps with other activities and outings can help your brain (and other parts...) figure out which is which and how they feel together and in which types of people. Fun stuff all around, but exhausting for sure!