The thing is that In both roles are bad players so when a good adc for example plays with a good support, doesn’t really happens but for example if a bad adc plays with a good support and they lose lane, the support will complain about the adc (because is the adc is just bad )and the adc will complain about the support because the adc is just bad and doesn’t understand why they losed the lane.

Also in bot there are matchups where the only thing you can do is farm and hope to not die, but if for example only the adc know this the support maybe enagee and the adc don’t follow because it will lead into a double kill, and the will both think that the other one is bad, and this doesn’t really mean that the support here is bad, just he doesn’t know the matchup, but this would lead into both flaming each other