If someone is trying to offer constructive criticism and they are either positive or neutral in their tone, then they are merely trying to help you make yourself a better asset to your team.
They might be correct, they might not be correct. But it should at least make you consider choices you've made that resulted in the death of you or your allies champions, the loss of turrets, or even missed opportunities such as dragons, the herald, and baron.
If someone is issuing insults your way and/or at your expense in allied chat and, more often than not, all chat, simply to express their anger and frustration over your choices and actions then it is best merely to mute them, report them after the match if you so choose, and then add them to your list of blocked players..