I'm not sure to which meetups you are going, but Meetup.com is just a platform with a great reach. There'll always be corporate sponsored meetups in cities, but if there would be no Meetup.com they'd post it on Twitter or sponsor conferences in the city. I actually like it to check out other offices in the city from time to time and I don't mind the one talk from a person of that company, it's just fair as they provide the venue and food.

Especially if you are coming to a new city it's a great place to find out what's going on and find your group. It's nice to have a centralized place for that and makes it very easy to connect with people. (At least in my experience here in Berlin)