[Tagging] type=route tagged on a way?

[osm.tagging at thorsten.engler.id.au]

I've noticed there are 9377 cases of type=route tagged on ways instead of
relations:

 

https://taginfo.openstreetmap.org/tags/type=route

 

I've been unable to find any documentation of this tagging approach on the
wiki.

 

https://wiki.openstreetmap.org/wiki/Relation:route#Route_types_.28route.29
seems to indicate that certain route=* values can be tagged on ways in
addition to relations, specifically ferry, mtb, and nordic_walking.

 

But even in that case, type=route on a way seems to be wrong?

 

An overpass query excluding these 3 route types shows that the majority of
these 9377 ways don't fall into these specific route categories:
https://overpass-turbo.eu/s/yTU

 

So my question is, is this type of tagging actually supported by data
consumers, or are these 9000 tagging errors?

 

Cheers,

Thorsten

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