Most regimental cap badges were made out of brass at one time so I can see where someone may have come up with the term BUT they are cap badges. The newer badges like logistics are made from white metal with a gold coloured wash on them and enamel (paint). These are available in cloth, gold wire (for officers) or a mix of the two (also for officers). No brass. Frankly, if a cadet corps C.O. somewhere, who used to be in the navy, decides to change army vernacular, let him have his little empire but the facts remain the same, it's cap badges.
As far as guys that collect them, great. There are thousands of cap badges that have been worn over the years. When you consider the pre World War One regiments, the C.E.F. battalions, the post WW1 units and the WW2 badges, the changes that occurred when the Queen ascended the throne, there really are thousands of them. Some are very common, like the Artillery badge and some are quite rare, like the Garrison Battalion of WW2 or the 7th Mounted Rifle Battalion of World War One. For you guys that want to collect cap badges, welcome to the hobby. A little word of advice, start off collecting the badges that you unit ever wore, then go after all the badges in your brigade. Have some fun trying to find them all and take the time to learn the histories of the units.