It never caught on, no, which is a shame because you can have multiple layouts by changing the size of the tab in the options so if I wish to see 2 spaces per tab or 8 its up to me to decide while the source editing is left unchanged.
Yes, that was the theory. Shame it never worked in practice, except for the most limited uses, because touching it with anything else would corrupt the layout completely.
And if you got source from somebody, you had to guestimate the intended tab size first. And
Arcane though? Oh wait, what do you mean by arcane?
Obscure, from a forgotten era. It is not used that much anymore to my knowledge, except in some unix config files (and even there it is lessening, Linux was always much more tolerant to this than e.g. BSD) , though every so and so often somebody reinvents it, and thinks it is great. It isn't.