The engines then 'back off a notch' so they don't exceed EGT limits.
If the engines are in good health they shouldn't reach the EGT limit anyway, even on a very hot day.
But if r/w available, TOGW, obstacles etc. permit, then it's prudent to use flex to bring EGT back down as much as feasible. It's less of a safety issue than an economic one; keep engines in shape longer, with attendant longterm fuel savings and maintenance cost benefit.