Like. It's far from impossible that at least some of these keysmash brands are actually a really good value and effective, meeting or exceeding their claimed capacity. But the problem is, most people don't have the means to test how effective it actually is. It's a complete crapshoot on if you're buying a product that will do what it claims it will do.
I can't really be confident that LEVOIT will actually be able to maintain a safe level of air pollution in a home currently beset by THE FOG, and I'm sure people actually living in a place scrambling to find a good air purifier are even more frustrated to see no recognizable brands that might be able to inspire confidence that it can make their home habitable. Or one that is unlikely to break on them during continuous use if it does work adequately.