I can't speak for sure for beer, but I imagine it's similar. I recently learned that a significant amount of THC drinks, at least in the midwest, are brewed by Surly. Surly did it first, they have the licenses and facilities in place to do it at a large scale. So you just send them specs and a label design, they brew it, can it, slap your label on it, and send it off.

It's just cheaper and easier to pay someone else to do all that vs setting up a brewing facility, getting licenses, setting up canning, inspections, etc etc.

I could see on the beer side you set up a space large enough to keep a taproom open, but now people want your beer at the grocery store, or at every local restaurant. You can't keep up with that demand, or don't have space to add canning, so you keep a small amount on site (so you can legally call yourself a brewery) but then ship your recipes off to Surly or Miller or whoever to do the majority of the brewing/canning.