My player has found out that one doesn't need magic to cast Fireball.

So now he is walking around with 20 Basic Grenades, throwing them like Oprah Winfrey during a giveaway show.

I am not planning to nerf his playstyle, but he keeps insisting it is a meta playstyle, planning to ditch his weapons to just use grenades instead.

So I am conflicted as to how I should proceed.