A wide and full tree will enable Ancestry to present Common Ancestor hints and Thrulines hints a small barebones tree will not do this.
You have a different definition of a bare bones tree to me. My Ancestry tree contains over 3,000 individuals, with their relationships, ancestors, descendants, collateral lines, and summary information for facts an events. So, for instance, it includes the dates and locations of births, baptisms, marriages, deaths, appearances in censuses, occupations etc. where they are known. What it does not include from my offline tree are the sources for that information, any media such as image of source documents, places or people, or my notes and other research information.
It is perfectly capable of obtaining record hints, common ancestor hints and Thrulines suggestions.
The export function in my software can track accepted or viewed hints in such a way that they are not repeated when I upload an updated Gedcom, but I have never felt the need to use that aspect of the software. Any new sources or information discovered as a result of Ancestry, FindMyPast or other hints and matches I download, source and cite in my offline tree. That information will make its way into subsequent uploads of updated Gedcoms, but only as summarised facts. It works for me.