aceplace57, the reason your Granddad didn’t keep a stallion is that they’re a huge PITA and can be dangerous.
It’s difficult to tell from the article, but it sounds like the problem is transporting the mare to breed. IIRC, this is common in Thoroughbreds, because the TB registry doesn’t accept artificial inseminations. I don’t know how common it is for other breeders; I’d think most have gone AI to avoid transport costs and problems.
I don’t think AI of a mare that wasn’t transported would cause problems. The article doesn’t really exactly say, but the problem seems to be the ‘going away, coming back pregnant’ (or alternatively, getting pregnant and then a new stallion coming in).
It’s also not a problem if you’re not keeping your own stallion, it seems to be the proximity to a “new” stallion that causes the problem.
I suppose it’s possible that either stallion or dam could somehow figure out that a foal wasn’t his even if the mare never left, but I have my doubts.
Male lions just kill all existing cubs when they take over a pack (and IIRC any born very soon thereafter). They don’t count down the months to know when their cubs start showing up. And lion gestation is only 3 months, not the almost-year that horses carry!