Again, so? I don't see the relevance of this to the point I was making. It is a nonsequitor to the idea to which you responded.
Let's say a necromancer and a chronurgist were engaged in battle. Each has their focus. Let's say that each is also only limited to their focus. Which of the following is more evocative and interesting?
Necromancer: I use Vampiric Touch ... 19 to hit ... and ... deal 22 damage. I heal 11.
Chronurgist: I cast Slow on him. DC 16 Wisdom.
Necromancer: 18 save. I cast Danse Macabre and have the 5 skeletons attack. 13,16,8,15,18.
Chronurgist: 2 hit.
Necromancer: 7 and 6 damage. Total 13.
Chronurgist: OK. Time Ravage? DC 16 Constitution. 85 necrotic damage if you fail plus a buncg of effects. Half on a successful save.
Necromancer: I'm resistant . Fail the save, still take 42.
Chronurgist. But you die in 30 days, have disadvantage on attack rolls, saves and ability checks - and move half speed. You need a 9th level spell to fix it.
Or:
Necromancer: I use Vampiric Touch ... 19 to hit ... and ... deal 22 damage. I heal 11.
Chronurgist: Wait a second: I cast slow as a reaction. When cast this way, it gives you disadvantage on the attack. As you rech out to hit me, I use the slow magic to give me a chance to dodge!
Necromancer: Doh! 12 ... that missed, right?
Chronurgist: Yup. OK. I'll go for Time Ravage. DC 16 Constitution. 85 necrotic damage if you fail plus a bunch of effects. Half on a successful save.
Necromancer: I use Tether Essence's reaction - make a Constitution Save yourself. DC 17.
Chronurgist: As a reaction I use Temporal Leap and jump forward 1d6 rounds in time, avoiding the Tether Essence.
Necromancer: Nice. I'm resistant. I fail the save, but still take 42.
Chronurgist. But you die in 30 days, have disadvantage on attack rolls, saves and ability checks - and move half speed. You need a 9th level spell to fix it.
Necromancer: OK, but I'm casting Danse Macabre to get ready for when you reappear.
This is not a new idea, but it is an idea that has never been executed well in D&D. Instead, we drop a few reaction defense spells in the game and call it a day. They get kind of boring. I'd rather they dropped shield, absorb elements, silvery barbs, counterspell, and other reaction defense spells in favor of giving each existing spell a reaction use that was defensive or battlefield control related (grease, web, etc...)