Oh for sure, ACE isn't the only useful measure of a season. But, if you have nearly 30 named storms with an ACE value of around 150, it tells you something about those storms in general vs. if the ACE were around 250. It tells you that conditions were insanely favorable for tropical cyclongenesis in the Atlantic in 2020, but for whatever reason did not support Irma or Ivan-caliber, 40-70 ACE beasts that maintain clear stadium eyes for days on end. That's all it does. Of course it doesn't tell you anything about impacts, nor is it designed to.