Nope not crazy! My sisters are I all sleep on belly from 6 weeks and my children have done the same.
When i went to a pead he said to me " If they vomit while on there back they tend to turn their head but doesnt always happen" And I dont want my kiddies with flat bald heads!! And i just dont swaddle them and have toys and crapo around the cot! EASY!!

2 of mine have loved it and the next one on the way will be the same!