I think a lot of people don't want to even do THAT much to grow palms in unpalmy locations or places too cold for a palm or subtropical plant.
I think many are more willing to do the extra work when they are younger, or when they first begin experimenting with out-of-zone plants. After a handful of years, it gets old. You get to the point where doing anything more than laying down a thick mulch is a pain in the butt.
When I found this board 11 years ago, I remember what the pitch was. In Zone 7, you could grow Zone 8 palms without protection as long as you DID protect them for the first three years. The idea was that after 3 years of establishment, a Zone 8 palm became a Zone 7 palm. But "establishment" kind of turned out to be a little overhyped. I think a palm can gain half a zone with establishment. And, in a great microclimate, you can gain another half zone. But that's about it. So, 7a can, theoretically, grow well-located 8a palms (Needles & Minors), after establishment, with very little protection AND very little chance of losing the palm outright. But, I don't believe 8b palms (Trachies, Palmettos, Butia, Med Fans, Washies) can make it in 7a without lots of help. In a solidly 7b location, 8b palms might make it -- again, with great siting.
The long and short of it is to grow a palm TREE (that you can sit in the shade of) north of the MD/VA state line on the peninsula is challenging without protection. And it's out of the question from Dover, DE northward.
THAT'S why you see the craze having died down. The hype kind of killed itself. Growing palms out of zone is work. And people with full-time jobs in their 40s, 50s and older are just too tired at the end of a day to build shelters, run outdoor electrical lines out to their plants, and do all the other jumping through hoops that are required.
Having said ALL that... All I ever lost outright since 2007 were a Brazoria, a Palmetto, an Oleander, and a Bayleaf. What has survived all this time were/are another Bayleaf, another Palmetto, a Trachy, 2 Minors, a Birmingham, 2 Needles, and a Live Oak.
If I had it to do all over again? More Needles and more hardy faux subtropicals like Yuccas, Daphniphyllum Macropodum, and Aucubas. I'd stay out of the Trachy and Palmetto business.
Sorry for the LONG dissertation, but it's a worthy subject.