To those that think rinsing is stupid and inconsiderate to those waiting at the dump station, be glad you don't own my last trailer. It had a long flat tank with the toilet inlet on the opposite side of the outlet.
I never dumped without nearly filling it with water to start with including dumping dishwater down the toilet, I would take a few loops around the campground to slosh it about and then pull up to the dump station which are never level compounding the problem.
It would drain slow and if I couldn't rinse and rinse long, one look down the toilet would tell you that a substantial amount of solids would remain.
Rinsing for some is very necessary. I am fortunate enough to have a dump at home and many times finished the rinse when I got home. When I was going from a no hookup CG to another without hookups, well you just had to wait behind me in line at the dump station.