Like @GaryVoshol said: it’s not about the robot, it’s about the venue.
The bar to entry in a water is higher than current FRC, so as an organization we will have fewer basically-functional teams (something we should want to avoid). That challenge pales in comparison to the logistical challenge.
Picture this: you’re a HS super/principle. An outside organization asks you to host a competition. You need a pool or a floor capable of sustaining the load of a pool. If there is a mistake made by the volunteer assembling a pool thousands of gallons of water will get dumped into your building. If you already have a pool and robot goes pop underwater and battery chemicals/oils/whatever gets into the water you need to change it. Filling, or changing, pool water usually means trucking in thousands of gallons of water, you can’t just flip on a tap and wait.
All of the participating teams need a pool of their own to test in, which brings along all of the same challenges as a venue, only each team is responsible for their own. This might be fine for the southern states, on the other hand I’d be pissed if I had to go out onto the lake a hack a hole in the ice to test a robot.