While 3D Tropical Service Dress has actually been removed from the CAF dress instructions, I can understand someone wearing it if in a tropical environment if they still have a closet full of the stuff. Still a little rebellious, but it is issued (if obselete) kit. That isn’t an option for most of us, as it’s no longer in the manual, so it won’t be issued. I have a PDF dress manual dated 2017, which still has 3D, so it’s removal has been fairly recent.
While 3D was widely mocked for the optional shorts and knee socks, the long-trousered version is very useful in certain niche positions, those posted to a hot environment yet whose workplace is a little too formal for CADPAT.