This does not make sense I don’t expect every single site I visit to explain the fundamentals of everything.
https://www.youtube.com/watch?v=qp0HIF3SfI4
Of course, it's their choice. But don't conflate that with being the best thing for the project or the visitor. Presumably the site exists to convince people to use it, no?
While I'm completely in favour of having documentation that is explicit, there is a fine line between that and flooding your landing page with super basic content that doesn't help your target audience just so that those who don't need this can understand why they don't need it. If you can't understand why that is a problem then think for a moment who the audience is and why it's important that your content be tailored for them.
Clearly, it's not as common a term as you believe that it is.
Though it does sound like you operate in a different domain. I’ve generally heard the term in relation to sysadmin and related fields. While there’s nothing stopping an electrical engineer nor inventors from having a home lab I’ve generally heard them talk about their environment in more physical terms (eg soldering station) whereas a home lab (in computing context) is often just a rack in a cupboard. So it’s more of an ethereal space. This is all hugely generally speaking, of course. But it might go some what into explaining why you hadn’t heard of the term before.