For the longer distances, over 1,000 miles, sometimes folks would rather get there quicker by truck/trailer for a variety of reasons. One of them is limited vacation time. Another is physical, as Hubbard mentions. When I was younger, as with a lot of other things, I did not really understand the trailer deal. We rode everywhere. No trailer. Aches & pains plus not dealing with weather events has changed my perspective.
Was at a condo for part of BikeWeek & at a motel for the last weekend. Many trailers, some carrying bikes that were not road trip friendly. Also many bikes, some from a great distance, no trailers. My take on it is: each person rides their own ride, the way they want to ride it. If that includes a trailer, well, for them the ride starts when they drop the bike off that trailer. For those who have no trailer, hate the idea of trailering, yes that is your decision.
We know folks who have never ridden over a hundred miles from home - they always trailer. Even from here to Panama City which is less than 100 miles. Know folks who have never trailered, never plan to. Wife & I have taken multi thousand mile bike trips on the bike only - no trailer. Have also done this with the bike on a trailer. Circumstances dictate this decision for us. Figure is the same for others.