It's likely a legal thing....should be no problem riding it up the ramps into the bed.
Now, let me get on my soap box for a minute. When I was working at the dealership, I was loading and unloading customers machines in and out of their trucks, usually with them standing right there, as many as 50 times a day I bet.
I would never, ever, ever, load or unload a machine without a tie down strap running from one of the rungs on the ramps, to their trailer hitch, pulled tight. As you go in and out, the suspension is compression and releasing, which changes the height of the load. Going down, as the machine leaves the bed, the suspension goes up, it can be enough that the ramps actually slip off of the bed of the truck. Not good.
If you're going up, there is the possibility, that the machine with spit the ramps out as soon as the front wheels get on the tailgate, and the rears on still on the ramp.
If you have a trifold ramp, only one strap is needed. If you have two separate ramps, you need a strap on each ramp.
I am completely positive that had I not done this, I would have had the ramp fall out from under me, a couple of times. After the ramp was strapped down, I crawled up the ramps in low gear, and 4x4 mode, to make sure I did not hit their back glass.
If you load or unload from your truck without a strap securing your ramps to your truck, you ARE playing a form of Russian roulette. Please do not do it.
It takes you 3 seconds to strap down the ramp to the trailer hitch....seriously. And you can use the strap to tie down the machine once its in the bed too!
Okay...hoping off my soap box now.
Working at the shop, I have seen customers who where loading or unloading their own machines at the shop have the ramps come out, going both down and up. I've also seen a customer smash out his own back window with his winch loading his machine in.