Three of my friends used every exploitative way BG or some other website posted to level quickly, since release. I highly doubt they were intended forms of exp since they were fixed (obviously). And I'm not going to list them off because 1) I'm not even sure if I'm allowed to here, 2) you want to know you can do some research yourself. That being said I don't understand the "I'm just smarter because I leveled quicker" argument. I also don't understand the "everyone stabbed Cesar so I did it too" argument. Obviously something that is wrong is still wrong even if a million people decided to do it.
Where it comes into harming the experience of the game... My three friends, and a majority of the linkshell we made together all have maxed out accounts. These people rushed through whatever content was available and simply don't want to do anything but max tier stuff. Honestly I don't even feel they have a right to be grinding high tier stuff without even learning to play their characters, but that is another issue alltogether.
Part of the whole mmo experience is playing and leveling with friends, something that I can't do now because of them abusing exploits. Me playing with them these days amounts to an hour of them pretending to powerlevel me (and failing at it because they don't understand a majority of the game mechanics), them making it seem like I owe them a favor, then me just telling them to go because I'm not having any of that. I'd just go out and make some new friends to play with but that's kinda hard with such a low pop game... Most of the people I meet don't even speak english.
For those of you that played FF11 or hell, even WoW or some other MMO... You cannot tell me that you didnt have fun leveling with random people and your friends... Since I started playing again I see maybe one or two people my level range who refuse to talk/respond to me. The second I start killing in their camp hoping they notice and invite me, they switch to their 50 and kill everything in site till I leave... I just feel like there is not enough of a true low level presence in the game.