I haven't heard that before and i find weird that a publisher that releases a game on a DRM-free game will have some need for a *launcher*. Where did you read that?
I don't know if this is true or not, but it wouldn't surprise me. Game companies, like most companies nowadays, are hungry for two things: money and data. Launchers, particularly launchers connected to a store, make prompting people to buy DLC easier. They're also useful platforms for advertising upcoming games.
From the data angle, launchers can keep track of who's playing what for how long, along with what a storefront might offer (purchases/wishlists/views/ratings). Launchers won't just do this for a particular dev's games, either, so that gives them better insights into current gameplay trends (while nicely avoiding anti-collusion laws and having to pay for that development maintenance yourself).