The idea really has nothing to do with setup time but rather relative comfort on the road vs. at a camp site. Now, I'll preface this by saying that I've never had a RV with slideouts, but I think fivers are more comfy than a motorhome and 1 ton pickups don't have the smooth ride of a motorhome. Therefore, if you're on the road a lot, a motorhome will likely be more comfortable whereas the extra room in a fiver (per foot, not needing room for propulsion) would be more comfortable on the campsite.
And maybe you guys are the exception to the setup time, but if it takes me more than 15 minutes from backing in the motorhome to drinks in hand, I'm doing something wrong. I haven't personally witnessed a fiver setup taking anywhere near that short.
The crush zone argument is moot when several tons of trailer comes through your back window.
