Each to their own. Plenty of evidence of professionals using a wide range of techniques out there,
including microsponges (which are not dry powder, incidentally). It's very easy to
demonstrate the superiority of microsponges over other techniques for real-world domestic usage.
I agree. The people that usually have never cleaned their carpets believe that “cleaning carpets makes them attract dirt.”
Resoiling is a known phenomenon with multiple causes. These include wick back to sticky chemical residue that results in faster resoiling. So, there is some truth to their claim, although that's not an excuse to correctly clean a carpet in need.
For service-providing or commercial usage, microsponges with appropriate equipment for larger scale delivery is superior, according to data available in the literature. Some extreme soiling may benefit from pre-clean with steam extraction, prior to microsponge final cleaning for best results (microbiologically and resoiling). In general, water should be avoided on fitted carpets for many reasons covered in the links above, but carpets that are extremely abused and neglected will not particularly suffer if it's used initially, or if a wet stain has already occurred.
Many will disagree with this but I guarantee they will present absolutely no convincing objective evidence to support their position, distinct from that provided above and further correctly conducted fact-checks. That's how you know you can safely discard such subjective sources.
