Having played FanDuel, I'd buy the argument about skill if they weren't pushing you so hard toward, and the app wasn't geared to, playing often. I seriously doubt one could play so frequently with any degree of skill, unless it was a full-time job.
For the most skilled players, it would certainly be worth it to them to treat it as a full time job. They make more doing that than most jobs.
I think that's true in the same sense that it makes sense for someone to quit their job and sell Mary Kay. The exceptions that have the big downlines and the pink Cadillacs don't disprove the reality of average performance. (per annum, average salesperson makes less than $100)