If you write this sentence in the pregame chat...
_"Hi, premade with [name goes here] we would prefer bot"_
...players like me will happily pick one of the other three roles to give you your spots.
However: If you write this sentence into the pregame chat:
_"bot premade, if you pick bot = insta 2x report"_
...players like me will 1. say nothing, 2. try a new champion, and 3. report you after the game.
Manners. It all comes down to manners.