it has probably happened through out history where well established names get hijacked when something else get picked up by the general population. e.g.
hacker vs cracker.
drones (rc helicopters vs pilotless aircraft).
I agree with your wider point, but the antonym of broadband in networking context is actually baseband.
'Narrowband' is a good example of a word that came into use to fill a perceived gap in the lexicon. A gap which didn't really exist, but the word became more widely used because it was not challenged by people who should know better.
Another example is 'bandwidth' which has so many colloquial meanings now that it is unusable in any general context. It's just a collection of letters that can mean anything you want. Also 'hacker'.
This is not the evolution of languge, it is its destruction. Overloading words with so many contrary or ambiguous meanings that language fails at its primary purpose of conveying meaning and intent.