I did thousands of miles on a road bike in my younger years, and when I decided to buy an e-bike this year a test rode a bunch. I don’t think the vibration and bumps of an unsuspended fork would prevent me from doing a 50 mile ride, the human body is pretty darn good at handling it. But due to the comfort of a quality suspended fork, I wouldn’t even consider a rigid now. Maybe in warm weather climates where the roads don’t go through numerous freeze-thaw cycles every year...maybe those areas have glass smooth roads. I’m in a 4 seasons climate and the difference in comfort between rigid and suspended forks was significant.