No, it’s the AA values not being on a sliding scale. If you cap out fighters at 6 dice and ships at 7 in 1939-40, it lets the early war bombers have a chance. That’s why the teams have such a hard time with making historically relevant planes useful.
And by the way, could you please just create an account so we know who you are?
I've tried sweeping mines in a few games but those ships that have that ability are kind of a liability as they have very low armor ratings. Any Aircraft that are capable of laying mines are always in any fleet built of mine.