I definitely went down the rabbit hole after reading the article posted, which was very well compiled. Their testing and reviews are very high quality and it looks like they can apply their test results to multiple curated use cases. Their tests also seem repeatable, which is important for this niche. To branch out, they would have to build out very specific testing environments, which is not a small investment, depending on what they are testing. If I ever need an air purifier, I know where to look now I guess. Like some say, if your going to do something, focus on doing one thing and do it well.