But their resources don't deplete. They can keep swinging the sword (magic or not) and making skill checks all the live long day.
The game is designed around "punishing," yes. Anything less can obviously be perfectly fun, folks do it all the time. But if a group doesn't care about resource attrition, then they are unlikely to be concerned with relative resource use.
Right because hit points don't create a "day" limit for everyone... and often moreso for the
classes who melee more.
And again, the problem is:
(1) 5e's balance is centered around a workday of 6-8 encounters. Let us assume 8 encounters; 5 Combat and some combination of 3 that is broken out into Exploration and Social.
(2) Given 1 (which is already a fair chunk of meaningful encounters), you're going to have how many truly weighty decision-points worth of attrition that wear-out a spellcaster's loadout? Regardless what that number is, its going to be roughly the same value
n for the level 9 wizard (let's use the Diviner) who has:
- only 5th level spell slots (and the related ability to up-level lower spells to there)
- 14 spell slots
- 4 Cantrips
- 2 uses of Portent
- 1 use of Divination refresh up to level 5
- Rituals up to level 5
...as it is for the 18th level Diviner who has:
- up to 9th level spell slot (and the related ability to up-level lower spells to there)
- 20 spell slots
- 5 Cantrips
- 3 uses of Portent
- Divination refresh up to level 9
- Rituals up to max level
- An At-Will level 1 spell and an At-Will level 2 spell (that they can switch out on Long Rest)
If you can't see how the intersection of (1) and (2) pushes back hard against the idea of "martial at-wills balance things out", then its virtually impossible to have this conversation. In order for it to 5e's attrition model to work, you would probably need roughly
n * 2 minimum weighty decision-points worth of Diviner attrition for the scaling of resource breadth, potency (MANY more "win condition" spells = less total decision-points required to resolve a conflict), and proliferation from the level 9 Diviner to the level 18. That means a HUGE (nonsensical) workday of something like 14-16 encounters (minimum probably).