Thanks for the memories Dave; I'm surprised you keep those old magazines. Its hard to throw those away, I feel the same passion for it; they are like old friends, but it just takes up extra room more than I'd ever refer back to them.
One thing nice about Ozzie electronics mags is, IIRC, they used as much US parts than British parts, so it was more applicable for those who were using US centric components.
One main driving force for DIY gear was economy, as we were all cash strapped, making my own test gear was the only way to afford decent equipment, and learned a lot doing so. This was also at a time a lot of professional stuff was still mostly hand made, 1970-90.
Today, if hobbyists model their projects around the same idea, it tends to not have the same motivation as Chinese electronics are far more low cost and where robots do assembly, can undercut any labor tremendously.
However, there many niches were devices do not exist for consumers or hobbyists mainly because the devices are either so low volume, or potentially illegal to manufacture. Non-lethal weapons like dazzlers or tasers, IR RF and cellphone jammers, camera auto-focus jammers, etc., are fairly easy to figure out the basics [ you can also build devices that are patented, but can't commercialize your project for obvious reasons].