In one case, it would have been pretty ridiculous for me to have gone to the ER given that I didn't otherwise have COVID or other serious symptoms.

In the other case, in spite of a pretty high fever, I'm quite confident that had I gone into the local rural ER at the time they would have had zero idea about the tropical disease I had and, even after I got home with a fairly persistent mild fever, my very experienced primary care MD just knew that my blood work looked bad and it took an on-call infectious disease specialist to know what was going on.

You're not always going to have an expert specialist available.

Not that it mattered in either case because there wasn't really anything they could do other than let my body do its thing.