Until 1982, military pensions were NOT dividable in a divorce.
They got nada. No matter how many years married.
That has changed since 1982. They can now get up to 50% even
if married one day.

To answer your premise, before 1982 the government did not
think the spouse had any worthy contribution and their pensions
were awarded ONLY to the military server.

Now, it is deemed unfair.
Government says so.

Personally, I think they do not serve.
They are just using words, not bullets.