A friend and I have developed some popcorn lung from cartridge vaping too much, but it was unusually heavy usage at an entire gram in a week. Most people can make a gram last more than a month and never encounter issues.
Heating element seems to have something to do with it. Most of those cartridges are cotton heating elements, but occasionally ceramic ones do exist. Ceramic or a quartz dish on a proper dab rig have never given me trouble.
Literally Elan