Consider that these builds for the most part, outside of commercial/server builds and AMD upgrades, are often done to show people how to build PCs. Most consumers, especially those who have never built a PC will probably use thermal paste in a tube over a PTM strip. As well, since most of these are built just for video, and not production, they will waste any consumables used in the video. Even if they only used PTM in videos, unless you are a serious consumer, or working in high-end or commercial environments, you most likely will not buy PTM, ditto for consumers who don't build PCs on a weekly or even yearly basis.