All brands everywhere because it's profitable. It's not just one guy.
It's private parties, retailers themselves, and overnight boom business etailers. Remember several years back when Dunhill went off the market for awhile? It was literally hours, not days or weeks, before it was sold out everywhere.
Like I said Cabelas in Louisville gets 25,000 rounds of 22lr per week.. That the equivalent of 50 bricks. And that's just one store. It's not a 'supply problem' at the moment, it's being produced. What I do fear is when the bubble burst and all these shops have standing orders for as much 22lr as possible with shelves over flowing with the stuff... It's going to effect the retailers, the distribution warehouses, the manufacturers...
As to why it exists? It's much simpler than it appears. The demand a few years back during the prime of "Obama is going to take our guns/cause a doomsday scenario" combined with massive federal orders that caused companies to produce the more profitable large caliber rounds with the limited components available caused a momentary hick up. People panicked and wiped out remaining supplies. The vultures set in. It's not rocket science dear.
And like you I do not really care why you do or do not believe it exist. You are allowed to be wrong if you chose.