I am starting to thing maybe chanties should not be called sailors' worksongs but rather, first and foremost, stevedores' worksongs.

If we think about it: Chanties were probably sung more by stevedores. On sea vessels, anchor-raising chanties would only be sung comparatively rarely—mainly in/out of port. So capstan/windlass chanties would not be sung so much, unless these devices were used as an alternative way to hoist yards and such. Halyard chanties would appear more often, but not constantly. Yes, there was pumping, too. It seems that most of the regular singing would be for the adjustments of sail direction and to tautness, i.e the so-called "sing-outs." And yet these sing-outs are not generally placed at the center of the concept of "chanties," and only a few authors on chanties give them much attention (for whatever reason—their relative "insignificance" is easy to imagine).

On the other hand, stevedores would be working "all day" to the singing of chanties. They would be closer in touch with the "land" songs that would inspire new creations.

And yet did many folklorists and such go out to collect songs from stevedores? There are certainly some studies, but are they not mostly studies of Black stevedores specifically? Other stevedore songs get mentioned only in the context of studies of sailors who heard them or also participated in that work. People didn't go out looking for retired stevedores to interview about their songs. (Stevedores, I suppose, did not figure in the national imagination of the "nautical heritage" of places like England.) While White stevedores were there, and I think of them in the observations of cotton stowing, no other observations of them are coming to mind, outside of mention in works about sailors.

It seems to me that this is a big gap, that probably shaped/skewed the narratives about chanties that developed.

In the least, chanties should really be called, IMO, "worksongs of sailors and stevedores." To define them first and foremost as just sailor songs may be a mischaracterization, that inadvertently marginalizes the stevedores' songs as something extra that one would include only when stretching the definition/discussion.