I'm a bit older now (late twenties), but when i was in my early twenties, i was flirting with people i wasn't interested in really (or only as friends). Because the stakes weren't as high, so i could just experiement without having any pressure. And gain experience so that i would be better equiped when i would flirt with people i actually liked (this rarely if ever happens).
Some people flirt because they're bored or want attention, that doesn't mean they now owe something to the other person, consent can be revoked at any time.

The only problem was when they would escalate propositions, or their ego got pumped up.
I got tired of giving free ego boosts, and eventually stopped flriting with people i didn't care about.

But i still think it's unrealistic to expect everyone who flirst to want to hang out with the person.

Especially since the boundaries of "flirting" are murky for people with poor social skills. How many guys think they female friends are flriting, just bc they're beign nice to them. There are some guys who are so desperate they think any girl who talks to them is flriting.

That's why i don't buy this "flirting = leading someone on".