Fixing cracks in drywall
Mesh and paper tape are really all about adding strength, which is especially important at seams or wherever the paper bonding surface of the underlying drywall may have torn or weakened.

In this case, if you're sure the underlying drywall is sound, then it means that the entire area of repair will be strong and supported from behind. So, joint compound should get the job done and stay strong. I'd suggest using setting type compound (sometimes referred to as "hot mud") for your first layer since it sets up harder and stronger than the drying type topping compound.