Of course theyre real people, unless youre playing with 9 bots.
Its extremely aggravating when people attack you and youre expected to just accept it and move on. Its such an asinine concept to be honest, and it allows these people to just continue being bullies against their teammates. If someone calls me out on what im doing im 100%, 10/10 times going to respond to defend myself because its human nature to do so.
I just got done with a game where I had my ally Ashe and Fizz pitching a fit because I was "stealing farm" from them, even though I only took farm when they weren't around or to try to fast push down a tower. This Ashe was also accusing me of baiting her to her death despise the fact that I was running to the tower with 1/3hp and she chased the enemy support ekko into river and proceeded to die to Ekko/Kat/Twitch, followed by myself because I tried to go in and save her with a windwall.
But I digress, if someone tries to accuse me of making a mistake or trolling or whatever and I haven't/aren't, im definitely going to defend myself. Muting them wouldn't stop them from being jerks, and robs myself of potentially important information later.
On the other hand, if someone is trolling you the best strategy is to ignore them. Most of the time trolls do what they do to try to get a rise out of their target(s), so denying them that is a good idea.