The bigger problem in United States profiles is that there are thousands of profiles that don't have 'any' country on the profile and have the 2 letter state abbreviation, or any other abbreviation, on them. Suggestions are not shown for the majority of those profiles.
Using wikitree+ with a query for any state abbreviation, and then check suggestions for the results, you can see the problem.
open birthlocation=<enter 2 letter state> birthcountry=unknowncountry not birthlocation="United States"