You care too much. If a bunch of baddies say they are going to report you, and you aren't usually a toxic player, then nothing will come of it.
Who cares if you couldn't report them, the fact that you just wanted to quit and tried so hard to report them means you got trolled hard and ate it all up. If you don't like someone, mute them in game. Don't tell them they're muted and be a drama queen about it, just mute and keep playing. If you want to report them after, cool. You can't? Who cares.
Does reporting do anything? Of course it does, go to the tribunal boards and read all the people complaining about how they got banned and didn't deserve it. They post their case and they were being complete dicks. You have to be a dick all the time to get in trouble, the thing is a lot of people that play this game are young so they don't get they are being negative or jerks and thus don't think they deserve their punishment.
Lastly, people are stupid so stop caring what they think. Olaf says no mia's yet you pinged mia, either hes a moron or you didn't ping in time. If you didn't ping in time then try better next time. If you did then hes a bad so don't get all butt hurt about it.
About the whole mia thing anyways, its a courtesy. If you die to a mia it means a) you don't have wards, are over extended, and don't use the mini map. b) you have wards but don't use the mini map and are probably over extended. Regardless of if there was a mia or not you failed not the lane that didn't call it. If they did call it you might have lived, but if you had been better then you would have also lived. Again, people are stupid.
If you like the game then play it and stop caring what people think.