I guess it depends how you define “popular”. According to Ohsome Dashboard, OSM has long had more kilometers of separately mapped footway=sidewalk ways than sidewalk=left/right/both/yes or sidewalk:left/right/both=yes combined. As of March 24, there were 832,782 kilometers (517,467 mi.) of footway=sidewalk ways. Even assuming for the sake of this comparison that every sidewalk=left/right is actually sidewalk=both, and double-counting the distance of every both way, that’s only 719,754 kilometers (447,234 mi.) of sidewalks tagged on roadways.
Whether mappers or data consumers are responsible for assigning street names to sidewalks, downgrading the majority of sidewalks to tags on roadways likely would cause dataloss. After all, tags aren’t very good at expressing geometry and topology.
Getting back on topic, this analysis does not consider the likelihood of an American mapper tagging every paved walkway as a footway=sidewalk. I don’t know how one would reliably account for any such confusion. That’s the problem with tagging something as a sidewalk just because locals informally call everything a sidewalk.