No one have any issues in sharing useful giveaways. I think, that rule is meant to avoid spammers, who just creates account, posts a thread and goes away. They won't come back again.
You may ask why limit giveaway threads only? Because giveaways are more attractive and gets more clicks....
PS : Personally I can trust a person who has 75 posts, because he has to be regular in order to do write so many posts.