What are you offering that they can’t offer themselves with their phones? Seriously. That’s the question you need to have an answer for.

In the old days, we avoided zooms because of all the extra glass needed to do the zoom part. A perfectly good prime lens might have 4-6 pieces of glass in it. A zoom lens a dozen of more (like a modern prime). Every extra piece of glass mattered. I guess it either somehow doesn’t anymore, or the cameras are designed to compensate in away not possible with film. I don’t know and I don’t own any of these monstrosities anyway.

But, the OP’s comparison is not really valid, since you really need to compare the weight (and hypothetical size) of 4 old prime lenses to one modern one to get close to the equivalent glass.