It’s pretty obvious that professional photography takes real skill if you’ve ever experienced the disaster of someone trying to cut costs by hiring an amateur photographer for a major event like a wedding but expecting professional results (the mismatch in expectations being the key cause of disaster here).

I’m not saying it turns out bad 100% of the time, but it’s easy to forget because good professionals make it look effortless. When the skill isn’t there, though, and you're used to only seeing professional photos it becomes very obvious (and again, that's perfectly fine if you're not expecting professional photography).

Even if we completely ignore the artistic and technical merit and complexity (which I would argue mostly moved to post-processing images) or the ability to catch or create the moments you want to capture, simply the fact that someone has to hold and point the camera makes it a job that will continue to exist. If you have a wedding and want pictures, someone has to take them. That won't be the bride or the groom, and shoving the responsibility onto one of the guests isn't nice (it would detract from their enjoyment of the event after all). So you hire someone to do it. Kind of like a job

You don't pay a photographer to click the shutter button; you pay them to handle all the details of composing a good shot, knowing what you'll want afterwards, etc.