The 25 gallon tank is enough to get me to the ocean and back with 10 gallons to spare. Out at sea I'm not motoring anywhere, at least not without carrying 100 gallons of fuel on deck in jerry cans.
Maybe boats these days have bigger fuel tanks but back when my boat was built people expected to have to sail or wait for wind. They also didn't have complex systems that needed a constant supply of energy.
And yet a good chunk of the most impressive sailing was done way back.