That's partly because power levels aren't assessed in isolation. In 3.5 if you wanted to take out a 20' radius worth of enemies you'd probably cast
Stinking Cloud. No spell resistance applied (unlike Fireball) and the enemies would lose all their actions except a single basic move for as long as they were in the cloud plus 1d4+1 rounds after moving out so a single failed save would incapacitate someone for a minimum of three rounds. A single spell and it would be clean-up against most of the enemies. And spell save DCs outscaled saving throws.
In 5e
Stinking Cloud (like almost all save-or-suck spells) is significantly worse; a save every round, constitution saves (which is a bad choice), and no "minimum of two rounds after leaving the cloud". And it's a 5e Concentration spell meaning it gets in the way of other spells.
The wizard is undoubtedly less powerful in 5e than 3.5. Fewer spells, worse spells, Concentration. Which is a good thing; 3.5 wizards were seriously overpowered. But fireball looks better by comparison because S-tier spells like Stinking Cloud have taken some much deserved savage nerfs.
I can't agree with you. The opportunity cost of Fireball in 3.5 was not taking an S tier spell like 3.5 Stinking Cloud. Fireball was C tier back then. In 5e Stinking Cloud and many of the other Save or Suck spells are C tier. Meanwhile Fireball B tier because it's the best way the wizard has of doing something useful can't be matched by anyone except the 2024 Druid at that level (2024 Conjure Animals is absurd as they broke emanations).
Except vs low CR mooks theyre failing saves 75-95% of the time just like 3E.
You gave hypnotic pattern, fear, slow trifecta. Druid emanating, cleric emanating, Bards can steal them and Warlocks it depends.
My party in dealing with are warlock, glanour bard, light cleric and sorcerer.
Any mook fight is irrelevant they have fireball but they have spirit guardians, radiance of the dawn, Hypnotic pattern, Synaptic static, fear, summons, hunger of hadar etc. And the alert feat.
Smaller group's have to dodge command, slow, Chromatic Orb, hold spells etc.
They have used fireball its been really good maybe twice 3 times max.
3.5 fireball was way better than 5E. Look at the amount of hp creatures had. Even better 3.0 less hp than 3.5. 10d6 often 15d6 via empower.
If 5E had a fireball that in effect dealt 30d6 or 45d6 damage which is an equivalent 3.5 fireball....
5E hp bliat is generally double or triple 3.5. Fireball wasn't ideal in 3.5. It was still better than 5E. A weak 3.5 fireball cast at 5th level is still the equivalent of 10d6 in 5E or more.
Dead is still a good debuff after all.
4HD ogre AD&D. Fireballs a save or die
3.5. Can still do it espicially empowered.
5E ogre better roll high it probably flunked both saves but survives 2 fireballs
Low CR critters are surviving 18d6 damage double taps in 5E (upcast fireball+synaptic static). After flunking both saves.
2 3.6 fireballs 20d6 flunked saves i woukd gave to go check the book but you're probably looking at CR8s dead depending on crotter. And those 10d6 ones are more likely 25-30d6 (one 5th level slot plus third level slot same as 5E). Assuming they can't empower it for free (its 3.5 it happens).
And fireball was "weak" in 3.5.
