It's no one else's business how another player chooses to gain their levels. If your friends preferred to get PLed rather than go at your pace, there's a discrepancy between what they wanted, and what you expected of them, since you feel so disappointed. You can't just blame PLing because your friend preferred it to going at your pace.

PLing in no way negatively effects anybody who doesn't care for it. Don't even try that tired argument of it leading to players on 50s that have no idea how to play their jobs effectively. Plenty of people in game that have 50s legitimately who have no flipping clue how to play their jobs, let alone possess the hand-eye coordination, timing, and overall common sense to be able to play effectively. In fact most people end up needing to be told how to play their jobs by people who have figured it out for them, which in no way has a prerequisite of having leveled your job legitimately.