The majority of people getting boosted DO NOT BUY GOLD. They have farmed the gold on their main character. The solution to gold buying is BAN THE GOLD BUYERS AND SELLERS, and not to ban the activities the bought gold is used for.
I have done DM:E jump runs for 4-5 hours with my warrior friend on my priest main, and the gold I HAVE LEGITIMATELY EARNED was enough to cover boosting my mage alt from levels 20 to 44, when I started soloing ZF GY zombies.
And, as you can see, even though I am not getting boosted at level 48, I still don’t join dungeons with regular levelers. I did one regular PuG ZF run for the carrot on a stick. It was horrible. The tank pulled 3 mobs at a time at most, and when I complained we are going too slow, he said “better safe than sorry”. That’s why I don’t do PuG runs. They are so inefficient. Do you know what would happen if boosting was banned? I would do spell cleave groups exclusively, just as I have done on my main at launch, with my fellow guildies. Never with you.
Boostees are the type of players WHO WILL NEVER EVER PLAY WITH YOU. Banning boosts will not help you.