Harder but obviously not physically impossible either. From the image I can't imagine what the showstopper would possibly be. Technician on a little dinghy instead of a stepladder doesn't seem like a big deal. Presumably they make it where you can pull the panel off easily if you need to.

You're talking about something that is probably at least 10x the cost to build and maintain. You're making something simple, like swapping a single solar panel, from a ground-level one-man job into now a multi-person job with specialized equipment and water hazards.