I’ve worked for companies that offer dry cleaning exclusively. One used cleaners that were formulated in the 1950’s, a whole three of them. One job I was only there because Chem Dry could not get a few spots out after trying everything they’ve got. The forty year old spotter formulation I was furnished to use took it right out; this told me everything I needed to know about Chem Dry as a company.
As a method, dry cleaning gained popularity because some steam cleaners got carpet so wet it caused problems. Of course the problem is you want to get carpet actually CLEAN, without causing damage either by overwetting or anything else. While I technically do offer dry cleaning, I have not seen a situation where it was the best tool for the job in a professional setting in many years so I’m not going to talk about it very much. More details are found in my section about common misconceptions.