I go up to the SHT every Memorial Day (it's an annual thing for me the past 5 years) and I've never had issues with traffic or finding places to camp. In fact last year I camped on the Split Rock River Loop which is a very popular area and there was no problem finding a place to camp.
The challenges with the SHT and a typical large HF type group hang event are parking (trail head lots are small) and finding a large multi group campsite close by. The reason I say close by is that typically folks are wanting to have the usual big communal BBQ's (lots of food, coolers, trash to pack out) etc. which lends itself more to a campground car camping type event. It's a PITA to have to haul all of that stuff on a long hike and then having to pack all of the trash out. I certainly wouldn't find that to be fun and isn't real practical.
On the other hand if the entire group wants to hike some miles and eat backpacking meals etc. then the SHT is great. It all comes down to what the majority of the group wants to do. Nothing wrong with either way, it should just be made clear up front so everyone knows what to expect.