There are many people who don't understand that the DTV is a new visa for new visitors. It appears to be taken as a relaxation of the rules for people who have managed to live in Thailand by using various visas and Visa Runs.
180 days is the maximum stay in Thailand without paying tax, so keeping things simple. Thai Boxing and Martial Arts, Cookery courses, Seminars, Conventions, Digital Nomads, Sportsmen, who currently visit and those who may become visitors are the target of this visa.
The rules for interpretation and implementation of the policy is up to individual Immigration Divisions. Presumably the Immigration Act must be followed regarding accommodation, staying longer than 90 day etc.historically they have been honoured in the breach and may be again.
My interpretation of the policy is that one extension of a maximum of 180 days may be applied for in country during the first 180 days for a fee of 10,000Bt. If that is done the DTV expires. That gives me the impression that the DTV is not intended for people to "visa run" for five years.