Could be they are getting older too :) Like many new converts to a belief system, there is a period of passion that mellows with time. So you touch the SUL barrier and then find yourself taking longer trips, or your 3oz wind pants get holes in them from just sitting down, and your gear pokes you in the kidneys through your sweaty frameless SUL pack, etc.
I noted the same trend with the articles on framed packs. There some upper weight limits imposed, but nothing like a 9oz SUL frameless pack. Certainly no 5 pound base weights in mind.
There might be some growing family influences too. Spartan SUL rigs are the bailiwick of young solo hikers. Add old bones on cold ground, unconverted hiking partners and/or kids and things get heavier. That doesn't mean throwing out all the good UL concepts, but your pack weight will increase if your partner won't sleep under a tarp or you take a 5 year old with you.
And I'll bet you run out of things to talk about. Okay, you made your 6oz stuff-sack-with-shoulder-straps pack and slept on a 1/8" pad with a quilt under a Cuben tarp. You find it works for a 6 week Summer window for overnighters, but there is the rest of the year, or you go on a 1000km trek through the Arctic, or haul 20 pounds of photo gear along with your personal kit. Those 5 pound base weights vanish with a couple feet of snow and windchill in the single digits.
Small organizations like BPL suffer from limited staff too. Much of the information of late is from two reviewers: Will Rietveld and Roger Caffin. Not that they haven't done a good job, but that is only two sets of eyes.
Backpacking and hiking covers a huge range of people, countries, climates, and purposes: day hiking, overnights, multi-day, thru-hikes, climbing, long-range expeditions, general travel, and classic trekking. I think a lot of the early stuff concentrated on pushing the limits and thru-hiking, but there are so many more hiking categories to investigate. There are comparatively few reviews given the wide range of uses and the flood of gear, so the focus may appear to be different.