Yep. Mahomes is about the only current quarterback/player I would trade three first round picks to get.
And you're right. I don't know the motive behind the question, but if it was to dis Dak, responses from posters saying they would give up three first round picks for him doesn't really tell us much because I wouldn't trade three first round picks for Brady, Rodgers, Wilson, Brees, Jackson or Watson right now. Brees, Rodgers and Brady are on the down side of their careers, Wilson, while great, just isn't someone I would give up three high picks for - maybe two - Jackson is one-dimensional and in about two years, he's going to decline if he's still running as much as he is and for Watson, I'm concerned about his durability.
Mahomes is young, tall, dynamic and would have had the Chiefs in the Super Bowl in his second year if not for Dee Ford jumping offsides against the Patriots in the 2018 AFC Championship Game.