For a reference, we can see that RuneScape gold the level rage in this first endgame seems to be in the mid 80s, based on the Grandmaster quests. Jagex has released a variety of sources of EXP and quick methods of training, such that levels in the ~85 range are not exceedingly far out of reach for new players. If you're a hardcore, there is still time to get to 90 levels. Each level comes with its own benefits, such as bonuses to combat or certain zones.
People are botting because they believe that the only thing they enjoy in runescape is pking and that training for the levels you can pk is boring. Botting has no impact on other players. It simply helps them stay clear of boring situations that might lead to them getting an excellent account for their pking.
In addition, I believe that the majority of people who play on private servers aren't there because they have been exiled or have different reasons. The majority of people use them to play and have fun without having to grind levels to get a good account.
After training my 3rd account of pking in 2010, I thought about botting. Anyone who has ever trained an account to play pking will know that it's tedious. In retrospect, I am fortunate that I didn't take botting accounts at the time. I made my decision partly on the basis of this fact that it wouldn't be a good idea to establish a Pking account via botting.
Jagex isn’t solving this problem. The concept of leveling up to pk seems to bore players who cheat. Players who wish to improve their levels in the classic method of killing mobs have been battling the same mobs over and over again, its always minotaurs or monks, or some other mob that grinds. So, I think the solution to botting issues caused by private servers and cheap RS gold pkers being so populated is that levelling should be fun.