Agreed, and the ease of 'assembling' various components is much easier now. Even the project in this article has very little soldering/individual components besides a few pull up resistors and some LEDs, both of which could have been on breakout boards. Everything else is just pin headers and jumpers to/from prebuilt boards.
The Heathkits and even things like the Radio Shack spring-wire 250-in-one type kits had you build circuits from all individual components: resistors, capacitors, diodes, transistors, inductors, etc. If lucky, maybe a few basic ICs like triple-nickels, op-amps, comparators. After hours of soldering/wiring you had something that did some very basic function - not a microcontroller/SBC with full programming language support and more power than a supercomputer a few decades ago.
Back in the day, kit radios were about as advanced as you could get with DIY electronics. You can still buy kit ham radios but the advancements that have been made in what is available for hackers is enormous. A full fleged computer the size of a deck of cards is amazing. This guy built an incredibly complex security system using off the shelf components that could have easily required zero soldering had he only used wireless sensors. His design is maybe a little over engineered (tamper switches on junction boxes?) and is probably much better than what any residential alarm company could offer.
Back in the 60's through the 90's we also had Haltech and Halted Specialties, electronics supplies and surplus in Sunnyvale/Santa Clara, each about a mile from each other.
Many folks confused the names.
As I recall, both of them had resident cats as well.
My High School electronics teacher turned me onto them in 1969.
It appears Haltech is defunct, and not surprising since the owner was OLD when I was shopping/browsing there in the 70's - 80's.
Oh, looks like Halted changed their name to HSC and may still be in business.
If you believe radio kits were as advanced as one could buy "back in the day", I guess you never looked at a HeathKit catalog, they offered all kinds of kits more sophisticated than radios.
In 1980 I got one of these kits for my auto repair shop, and yes, it was quite a challenge to build, but it saved me hours of automotive diagnostic time.
A comparable automotive ignition analyzer scope at the time was thousands of dollars.
The Heathkits and even things like the Radio Shack spring-wire 250-in-one type kits had you build circuits from all individual components: resistors, capacitors, diodes, transistors, inductors, etc. If lucky, maybe a few basic ICs like triple-nickels, op-amps, comparators. After hours of soldering/wiring you had something that did some very basic function - not a microcontroller/SBC with full programming language support and more power than a supercomputer a few decades ago.