Note: I meant to limit the changes just to the nodes in the Philippines, but my overpass clumsiness led me to edit nodes in other counties as well.

In any case, this isn't problematic, as I was going to do those edits anyway. I just wanted to separate them by country for more convenient inspection.

You're right, it is burdensome and unpractical for OSM editors. I am not aware of this being a common practice -- I just happened to need this personally, so I went ahead and "scratched the itch" :) of course, if there's a better way to fill the same need (now or eventually), I'll be happy to apply it.

Hi Josef. The relation is the only way to combine the various disjoint ways and identify the full avenue as a single object corresponding to the real-world location that people can refer to, associate to representations in other datasets (e.g. Wikidata), search for, use in addressing, etc.