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So when you need to remember a user/password combo for a new device, offline doorbell maybe, or a parcel number, or the address of a friend, then you record a 4K video instead of writing it in a text file? Plain text just works, everywhere, all the time.
> Plain text just works, everywhere, all the time. No it doesn't. Try a plain text description of an electronic circuit vs a circuit diagram. Try a a plain text instruction sheet vs an illustrated one. Try plain text sheet music vs actual sheet music. Try a mathematical plot vs plain text tables. Try concept drawings of product vs text descriptions. Try construction drawing vs plain text descriptions. I could go on a…
I'm not an EE, but there's SPICE for regular electronic circuits and SysVerilog et al for logic circuits. Math can be typeset in LaTeX, though its plain text readability depends on the formula. Category theory diagrams can be written in a simple language. Sheet music is some sort of XML, though I imagine there could be a more human writable/readable plain text format for this too. There was also a recent post about Markdown diagrams. And of course, code is still entirely text.
Much of what you mentioned can be described in a concise, portable text-based language. Though these documents are readable as text, they can be further rendered for best readability. Luckily, many can also be live previewed.