As regards the river basin. When applied to the respective countries individually (and without the "Republic of" qualifier), which are after all the context we're talking about here (not the river basin) it has an entirely different connotation. And again, there's simply no modern use case for "The Congo", by itself, as a name for either of these countries.
Whatsoever.
What connotation is that exactly? Does "The Virgin Islands", or "The Hague" for that matter, also have that connotation in your mind?
I am again just saying that there is nothing racist about the "the" in "The Congo". It is just a natural way to shorten "Republic of the Congo". It might be unusual nowadays, but that does not mean that there is anything pejorative about "The".
"Use case" has nothing to do with it, nothing about language use is fully "rational" or "optimal". It is obviously _possible_ to make do without the article, but what I am getting at is the misdirected anger some people seem to feel towards it.
The connotation of intentionally ignoring their very, very, very clearly stated preference as to what their official name is. Neither of these countries refer to themselves as "The Congo" as such, and they've made it known that they would prefer that you not do so as well. That's all there is to it.
"Use case" has nothing to do with it,
Au contraire. Language is all about use cases.
It's use cases über alles, in fact.