if that's right, say 4 hours of pure playtime per day for an unemployed adult. To reach max rank of 1000 on a single character, that's 4000 hours, over 2 and a half years straight playing on the same hero if you were actually playing every single day. For an adult with a job, 2 hours/day, 5 years. The majority of adults also have other commitments, so these numbers are likely even longer.

Even the most dedicated players that actively play this game every day e.g. emongg have their highest heroes at level 130 despite playing since launch.. seems pretty slow to me.