Another great article, Steve! The lead image of the giant Bluetooth speaker behind the family is hilarious.
As for the title question, I don't think the love of hi-fi audio is dead. But, as was mentioned, it is very much a niche hobby nowadays, at least two-channel hi-fi is. Much of it has transformed into home theater. I see a lot of guys obsess over home theater equipment much like the two-channel crowd that you describe. That obsession over the process of doing your homework, picking your components, and putting it all together is the same.
Also look how popular headphones have become. Hi-fi headphones are a much bigger thing now than it was 20 or 30 years ago, and it is younger people driving that hobby instead of retirees. It's the same thing.
I also think that many of the process-oriented people of which you speak are much more into putting together desktop computers nowadays rather than hi-fi stereos. Once upon a time, they might have been A/V nerds, but the nature of entertainment has changed, although the same personalities are there. Now they are piecing together computers instead of hi-fi systems. What video card to get? What computer case? Should it look like a colorful RBG explosion or should it look more restrained and sophisticated? How far can I push liquid cooling? What cable management techniques look the slickest?
If you look at the PC hobby, I think a lot of these guys are much more into parts evaluation, selection, and PC assembly than they are into the results. Sure, an optimized system can make some programs run a bit faster, but the time spent tweaking the system to net that extra performance is a lot more than the time saved loading a program or finishing a process. What is an extra 10 frames per second when you are already getting 120 FPS? I see a striking resemblance of the modern PC hobby to what Hi-fi used to be and to some extent still is.