I will never understand what is so bad about snowballing. I think it's the amazingly satisfying gift for playing really well. If it happens in too many games and you find the game too easy, increase difficulty. Ideally, the game should have a difficulty for which even playing really well you have a 50-50 chance of losing. Chopping the game into age transitions to kneecap people that play the game very well is very, very strange to me. It's like trying to make Magnus Carlson enjoy a chess game against a novice teenager and every time Magnus pulls ahead someone gives the teen three queens and a knight to even things out. Does anyone think Magnus would enjoy such games for long? If snowballing is an issue, all we need is competent AI. Not "rubber band" gimmicks.
My opinion is that interpreting "snowballing" as "playing the game very well" is misunderstanding what snowballing actually is.
Also, in your chess example, that wouldn't help the teenager beat Carlson, so. Not sure it's the best analogy. An experienced chess player might be able to do something with the sheer amount of bonus pieces, but a novice? Unlikely. Not that Age transitions are even redressing the scales that dramatically anyway.
Anyhow, when designing and implementing a video game, "all we need is competent AI" isn't very helpful (plus, it ignores the existence of MP). That's like me saying "well I need twice as many developers on my team". It's a nice idea, but it's not going to happen (for a multitude of reasons). AI should always be being made better, but AI is a research discipline first and foremost. The logistics of getting that effort (that expertise, and funding) into video games is something the entire industry struggles with.
Because of this, games are designed with constraints. These constraints are often set well in advance of any release-ready code being written. At their most flexible, they assume a best-case scenario depending on how implementation progresses (and will also have goals to settle for in worse-case scenarios, should they occur).
But ultimately this is all kinda irrelevant. You don't like feeling punished. It's an emotive (and valid!) argument against the game mechanic. Because it doesn't feel fun for you. Just like sitting there clicking next turn over and over waiting to lose doesn't feel fun for others. And not everyone likes to quit and start again just because they got unlucky, or the AI / another player got lucky, etc. This is the problem Firaxis have in trying to improve how the pacing of the game feels. People like different aspects of the game as it develops from the early game to the late game. This is truly what makes the late game in a 4x game tricky.
I think Ages are a good stab at it (as I've said before, I liked Dramatic Ages in VI for that reason). I think there's room for improvement, albeit maybe not for people that don't like to feel hindered by events outside of their control. Heaven knows I sympathise at times. The Barbarian balance in VI and V always felt either not enough pressure, or
way too much.