How do people sanely queue as 3+ marksmen?

Even if marksmen are FOTM, 2 is clearly pushing it. They have very few powerful tools for teamfights, terrible mobility, don't waveclear quickly and most either have very little utility or are among the most squishy champions in the game. The other two members of a 3-marksman team could be a tank and an enchanter and it would still obviously be an awful comp.