It's interesting how some terms take on a life of their own - as someone not very familiar with the intricacies of keyboards (and someone who has happily used the same membrane keyboard for ten years), I'm a bit puzzled that the term "mechanical" only applies to keyboards with individual switches. For me, any keyboard with moving keys is "mechanical", so only an on-screen keyboard may qualify as "non-mechanical".
BTW, do the good old "buckling spring" keyboards (https://en.wikipedia.org/wiki/Buckling_spring) qualify as "mechanical" by this categorization? I still have one of those (from an old IBM PS/1000, from the age before Windows keys) lying around somewhere...
In this context they aren't referring to the keyboard as "mechanical". They are indeed all mechanical. Mechanical Keyboard is just short for "Mechanical Switch Keyboard". I can see how it would be easily confusing for someone not into the hobby.
Buckling spring keyboards do indeed count as mechanical switch keyboards. I haven't used one since I was a kid but they were very cool.
That would be an IBM Model M, they are still quite popular in the community and Unicomp still makes them.
You should look up the model number.
Here's a good video on them: https://youtu.be/r5H58uudo1Y
BTW, do the good old "buckling spring" keyboards (https://en.wikipedia.org/wiki/Buckling_spring) qualify as "mechanical" by this categorization? I still have one of those (from an old IBM PS/1000, from the age before Windows keys) lying around somewhere...