I’m not convinced of that. There’s no way of knowing now - except by seeing how it works if it’s been fixed by the time the Steam players come online - but I personally believe that if they’d got it right first time round and not been tripped up by the savescum spike, hardly anyone would have noticed. As it is, they didn’t, and the difficulty spike brought it starkly front and centre to most people’s attention.
Now, it’s a ‘Thing’ and no-one can ignore it. In fact, I find it depressing that so many players on this forum seem to believe that it’s some evil plot by Snapshot to make their games more difficult, rather than an experiment in creating a universally level playing field that went horribly, horribly wrong.
I don’t think you do need any other ‘eg: apple’ parameters. At its simplest, it’s basically asking: “How badly hurt did the player get last time?” and adjusting the strength of its punches accordingly. It’s not bothered about whether you achieved the objective or did it in X turns - it’s simply trying to ensure that if you’ve set the game to Difficulty 0, you will suffer an average of 0 casualties per mission, but if you’ve set it to Difficulty 2, you are likely to take 2 casualties per mission.
Doesn’t matter, if you’re relying on in-game stats rather than end-of-mission results. So you lose 5 men and you save scum to get them back, so what? The game data still records that you lost 5 men… Ah, no, of course it doesn’t - it records the turn before you lose the 5 men. I see what you’re getting at now.
So the devs need to figure out a way of recording the game state as it was before a Restart or Reload - bit like the F12 button - so that the DDA gets the true picture of things, rather than the skewed picture the players are giving it.
Told you it wasn’t going to be as easy as it looked 
Or give players the option to readjust the game state by Resetting the Difficulty level.
As I’ve described elsewhere, I’m not good enough to survive the early game of most XCOMs on anything higher than Veteran, but I find that Vet gets far too easy as the game goes on, so I increase the Difficulty Level at the start of every Story Mission and that just about keeps it at the right level for me (though I had to take it back down in LW2 as I found myself getting slaughtered).
The point is, if the devs gave players the Option in the Menu to Reset the Difficulty - and this automatically reset the number of Nasties to the starting level of that Difficulty - the Spike would go away.
Personally, I think it’s very sad that;
a) a noble attempt to give players a dynamically adjusting difficulty state pitched at their optimal ability level was so botched at release that it’s become a ‘Thing’.
b) this has become a poor substitute for the Pandoran Evolution we were originally promised.