Did you also mention surfaces? With a single Firebolt cantrip, you can blow up your enemies if they are standing on grease, or more importantly if they are near barrels, torchstalks, etc. So, why use fireball when you can use a cantrip and a surface? Just as powerful.
Bah. What am I saying. Just shove. It's the most effective spell of all.
Fireball does more damage and you can combine it with grease...
Second resting doesn't work at all so a fireball is almost a cantrip:) IN short your example is a bad one but threads point is valid as is your point you'r trying to make.
In short:
No cover system = balanced moved to AC attacks
Loads of ways to get free/cheap AC advantage = balanced moved to AC attacks
As of right now no potions for casting stats = balanced moved to AC attacks
High ground +2 bonus to AC attacks that stacks with everything = balanced moved to AC attacks
Bardic Inspiration = balanced moved to AC attacks
Only a hand few ways to lower saving throws = balanced moved to AC attacks
anyone can use any scroll for any spell at any time = balanced moved to ranged and melee AC attack classes
Edit:
Shove = balanced moved to pushing enimies off the map for a easy bonus action kill.
