Are there any regulations/rules that say you must play that champ in that role?
When you see a Lulu go top, or a Nani go top, I question this in Ranked, so far I have seen off-meta champs go wrong roles and only cost me my promos or ranked tier. Now clearly you can't go and say they intentionally chose that champ just to have the excuse "Bad game", or bad matchup. End up losing your game because of lack of pressure or feeding (accidentally simply to arrogant to farm under tower).
What do you do? this of course is you can dodge in lobby knowing they going top, but man I can't dodge every match because some kid wants to ruin it?