District tartans, as a concept, may indeed be largely "irrelevant" to the majority of the current Scottish population, but I don't think that fact puts district tartans into the same category as "Irish kilts" or "Border clans." (Ideas that are popular today but have no historical precidence).

District tartans actually have a pedigree that is just as old and traditional as clan tartans and military tartans. It is simply a matter of the clan tartans becoming more popular and predominant in usage over time. Some of the oldest known named tartans are, in fact, named for places rather than clans or families.

To illustrate this point, one of the earliest sources we have available for "named" tartans is the 1819 Key Pattern Book of the weaving firm William Wilson & Sons of Bannockburn. That pattern book contains some 250 tartans, of which roughly 100 have names. While many are named for clans and regiments, some are named for places, including:
Aberdeen
Argyle
Atholl
Caledonia
Crieff
Dundee
Fort William
Gallowater
Glenorchy
Lochaber
Locheil
Mull
GlenLyon
Perth

Some of those I have named actually date much older than 1819. The Aberdeen tartan, for instance, we first find mentioned in a Wilsons' document dated 1794, and the notes in their 1819 book refer to the tartan being from the "middle of the 18th century."

Of course there are lots of clan tartans named in this source, as well. We find Chisholm and Austin and Forbes, MacDougall, MacNab, Gordon, Ross, Stuart, etc. But my point is that the concept of wearing tartans named for places is just as old and valid as the concept of wearing tartans named for clans and families.

I'm not disputing the fact that many living in Scotland today are unaware of district tartans, or if they are aware of them don't think them to be relevant. I would argue with the notion that district tartans are new or novel. While they have never been as popular as clan tartans, they are indeed just as traditional and valid.