Yeah it's probably a bit boring. But on the other hand, if we already have the three eras as separate games, it would make sense to utilize this to make it less of an end-game race, and more of an all three mini games matter? I mean, that's one of the points of a reset in games, in my opinion. Get a score for what you've achieved until then, strap down the game to some extent, and start anew with a fresh base and slightly different rules. It seems what civ 7 was going for as well. But if all that score from previous eras does is shave off 1-2 turns in the end, and give some mild bonuses for snowballing, it's quite useless as a mechanic.