I operated a photography business in Banff for 30 years and in addition to many other things, we shot lots of weddings. For the big ones we used medium format cameras but also 35mm and later digital. Neither I nor my other three photographers ever used more than one camera (although we brought backups). A 28 to 100 seemed to cover all the situations that arose but now I see photographers lugging two huge cameras often with long telephoto lenses and I can't figure out what they are doing with them. A 100mm lens is about the longest working distance that I would consider to be practical when shooting portraits, otherwise, you lose intimacy with your subject. I've been retired for twenty years and I am thankful I no longer shoot weddings, although I do portraiture on the side. It's a tough business.
First is redundancy - if one body fails, at least you've got a backup. Second is minimizing the need to change lenses. Most photography influencers today promote a kit that revolves around a 24/85 or 35/85 pair of primes, maybe throwing in a macro lens, a longer portrait prime, or a 70-200. I'm sure that many wedding shooters are happy to work with a single body and a 35-150, and I don't blame them. Maybe we're all brainwashed to buy more cameras and lenses than we need?