I don't punish players for this unless there is specific evidence (from their own admittance) that they are fully aware they should be doing 'x' but instead are choosing to do 'y' to force a loss.
Asking a player to group with the team, and they say "**** you guys, you don't deserve to win - I'm afk farming the jungle." I punish.
on the other hand, if they say nothing, or say something to suggest they believe what they are doing is going to help/good for the team (example "I need my <item> first" etc) then I pardon.
Every player has their own thoughts as to what they think will win the game(s). I don't penalize players for having, and believing that different strategies/activities are a good coarse of action (even if they are wrong).
I don't punish for unskilled (this includes players who may not say anything, and those who choose a losing strategy, thinking it's good).
It's unreasonable to expect players to take part in an activity that they genuinely think will lose the game (whether they are right, or wrong).
Some players may disagree with you (ignoring pings) or have you muted (so they can't hear you/pings) as far as I'm concerned there actions are not punishable unless they are refusing to listen to force a loss (intentionally). I consider it this report option very similar to grieving, and assisting the enemy team.