The existence of residential proxies like these is a massive pain if you run free trials or giveaways or host user-generated content (aka a spam/scam opportunity). DSLRoot is only one service of many (see last year's takedown of 911 S5 https://www.scworld.com/news/fbi-takes-down-911-s5-botnet-li... ) and there's plenty of demand for it.
Imagine getting hit by thousands+ of different IP addresses with different user agents, etc. Banning these IPs is not a great option - lots of collateral damage because many real people share IPs, depending on ISP setup.
I work on bot detection involving device fingerprinting - imo this is one of the only ways to defend against residential proxy activity, since you can sniff out the warning flags of automation software and other shared indicators regardless of IP.