Good question.
Nothing ever necessarily stays the same JKD and I daresay a certain migration to the convenience of mobile devices and social media has had an effect. I might venture also that a firm grip on the issues of trading cars and parts may have deterred some, as has the moderating of some legacy heated discussions on various topics. But I think it's the first reason mostly.
As you know the strict rules now applied to buying and selling are primarily as a responsibility toward members, some of whom in the past have been well and truly shafted by less-than-honest purveyors. The forum itself is no stranger to in-house dodgy personnel either, though this occurred some time back. The ethos is that we are basically a car-forum and not a stage for extremist views/language on whatever subject - there are plenty of other platforms for that. This may have appeared heavy-handed by some (and they're quite entitled to their opinion) and has made them reconsider their participation here.
I tend to agree that praise heaped upon the Fiat Coupe was boundless and often repeated in different ways but now appears to be lulled - even now though new members continue to be bowled over by this extraordinary beast which will be an icon of its time, I have no doubt, if it isn't one already.
Perhaps the great harvest of technical know-how on here might have changed over the years as the cars are very much reduced in number, though their age has brought up some new questions. Most of the common how-to's are already in place, leaving fewer to pose questions - apart from "what oil and how often should I check it"
In the end we have a forum that I think sticks by its guns, makes a genuine attempt to follow its rules and be there as a source of hard-earned info for the enthusiast. We also have behind-the-scenes volunteers who go to a lot of trouble to make sure we are legal, comply with GDPR, organise events for members in the UK and abroad and not forgetting, maintaining the IT!
It works for me.