This isn't true at the lower ranks, in addition to the lack of HP gear, the raw missing 16 levels worth of HP gains counterbalanced by the fact that you're entirely capable of reaching hero damage at level 35 if you get a hero set through pk, ranking has to occupy people's thought process.

Heroes on the other hand are either exploring, in which case they are usually exploring areas way too fucking dangerous to follow them in and happily PK their ass, or they are looking for a fight so there's no real way to catch them without them being in a guild to renew their preps. Thus, where multi-man cabal raid or pair gangs come in. Seriously, if you're not exploring and you're not raiding why shouldn't you be with your allies unless they're brain-dead?

Which makes thug thieves only dangerous in group fights at hero since their other dangerous abilities are all negated by nodisarm gear, anti_align weaponry, gobs of hP either via gear or con+class, and damage reduction out your anus because the mobs holding it half of them are lower level than you now.