I think the chemists have a point, but at the same time trying to be over-protective of language is often an exercise in futility.
There have been plenty of articles about an older generation complaining about the appropriate of the word "gay". For younger generations it's not something we have a problem with.
I would suggest that for chemists they might consider that the common usage of "chemical" is actually an abbreviation of "manufactured chemical" or some similarly accurate term.
Many parts of science are constantly misrepresented by those not involved in the specific subject area. That's just life.
This is a fascinating one because that word is shifting again: "gay" increasingly means "lame" rather than "homosexual". What's fascinating is how this is happening even as society becomes more tolerant of homosexuality. Young people who use "gay" this way belong to probably the least homophobic generation ever, so the politically correct misreading of this shift is even more off-base than political correctness usually is.
The South Park guys captured this perfectly with their line, "This is gayer than sex with men!"
All this by way of agreeing with you that the subtleties of language far surpass people's rigid attempts to nail them down. Incorrect usages that gain currency turn into correct usages. It's more interesting to observe and admire these shifts than to try to stop them (a fool's errand).
Edit: Man acts as though he were the shaper and master of language, while in fact language remains the master of man. - Heidegger