I know a few girls who were not allowed to date until after Succos of their first year back from seminary. I think that this is a very good idea. Post seminary girls need a few months to come back down to earth.
Someone mentioned above that the atmosphere in America is so not holy so girls should marry while they still have a taste if the kedusha of Eretz Yisroel.
These girls will live in America after marriage. Isn’t it better that they fall back down to earth before picking the guy they have to spend the rest of their lives with?
What happens when a girl, still on a spiritual high from seminary, marries a kollel guy. She loves it at first but then the excitement wears off and she realizes that kollel life is not for her. Had she come to this conclusion before marrying, things would have been a lot easier for her.
And not all seminaries are garbage. I’ll admit some are nothing more than fluff, but there are some really good ones.