Scenario: 1) I cast Armageddon/Wrath of God, 2) in response (instant stack) you cast/trigger effect that allows you to sacrifice (or return to hand) your permanents affected, 3) in response (adding to stack) I counter my own 'geddon/WoG.

How would this be possible when interrupts existed?

Pretty much how you described.

You have the original Wrath of God spell.

The effect or spell that allows you to sacrifice or bounce those things would be in the Instant batch.

The counterspell would be in the Interrupt batch.

The big difference is that once that counterspell is on the stack, you can't cast any more Instants.

So let's say that instead of countering the Wrath, you counter the spell that's bouncing all of the things. With the old system, that's it. If I don't have any Interrupts, we need to resolve our batches. No one can cast an Instant until we resolve both the Interrupt batch, the Instant batch, then the original spell.

Counterspells were even better before. They were effectively the last word. The stack kind of depowered them, but it gave a lot more play to the game.

IIRC, you couldn't counter the wrath once the instant is played (at least as of say 1998-ish rules interpretation).

I play Wrath. I can counter now, or let it resolve. You play instant effect. I can counter, but can't counter the wrath anymore. I'm pretty sure that's how it worked.

This is how messy it was. That could have been correct at some point. Instants and Interrupts, batches and windows were all way too much of a mess.