I don’t think so!
Mulder was a humper, but not specifically with intact girls, so I don’t think it was particularly due to him being an intact male. That’s just how he was (meaning I don’t think it was particularly sexual with him). I kept him as my only male with between 1-3 bitches for 15 years with no problems. It all comes down to training. Our Obedience training center encourages to people to bring their in season bitches to class just so that the intact males can learn to control themselves and continue to work despite the presence of an enticing girl in the vicinity. He would get distracted, sure, but we worked through it - and worked through it easier than the males of some other breeds that were there. When one of the girls was in season, there were about 3 days (probably when she was most fertile) where I had to either crate him or put him in an ex-pen to keep him from bothering her, but he never tried to escape or anything.
I know several breeders who have multiple males and females without issue (the puppies’ father’s breeder comes to mind). I suspect most of the people who seem to have problems are those who didn’t bother to properly train the dog in the first place and then had trouble with a large, strong, dog who never learned to listen who was faced with huge temptation. Just because the dogs aren’t pets, doesn’t mean they are properly trained. I’ve seen tons of conformation dogs at shows that were no where near as well-behaved and trained as I would like, but since this is usually an amiable breed it doesn’t usually cause that many problems when (for example) they drag their owner across the field to see another dog so people don’t always put the effort into training them as they should.