We see all the time words being 'dumbed down' by rampant misuse and therefore being added in the colloquial version to dictionarys. For instance, to any materials engineer, the word 'plastic' means formable. Therefore, a thermoplastic polymer (like the polyethylene in milk jugs) can be re-formed with the application of heat (melts) whereas a thermosetting polymer like the epoxy resin used as the matrix in a carbon fiber composite bicycle does not melt. Still you get bozos referring to carbon fiber composite bicycles as "plastic" because they have equated all polymers to the common "plastic" term. It's absolutely incorrect but it's still in the dictionary and wikipedia.

You can choose to be commonly dumb or you can be technically correct. Up to you. Instead of getting indignant because somebody pointed out a minor error (in a jovial way, no less), you could go the positive route and consider yourself more informed than you were before.