[gajomi]

It is a problem, but a technical problem thats well understood within the relevant communities. A quantification of "various tolerances" is one notion of diversity, but as you have deftly pointed out there are many other quantifiable notions that are endlessly debated (some links in the context of ecology: https://scholar.google.com/scholar?hl=en&as_sdt=0%2C48&q=%22...). Usually "diversity" is reported in terms of well defined quantitative metrics so that even if the umbrella term "diversity" is ambiguous it typically has well defined meaning(s) in the context of any particular study. All of which is to say, I would wager that the vast majority of scientific reports (and perhaps also those coming from the CDC) use the term "diversity" to introduce a general concept of a measure of heterogeneity which is quickly made precise within the study.