No, I think it makes the the experience strictly better for normal ("real") users. On phones it might burn too much battery, but on desktops or plugged in laptops dedicated users can configure their user agent to send in difficult proof of work submissions, getting closer to the front of the line. The actual problem starts when each individual request coming from the botnet starts submitting more proof of work then the real users can tolerate (due to taking too long), and that's where it's pretty much the same as before the DDoS protection system existed.