As seen in the most upvoted comment, you don't even need to level your character to be able to harvest max level source nodes because of some exploit or alternative, so the cost and time to get back up and running is classic wow gold minimal, and the total amount Blizzard earns from these accounts is also minimal.
As for"stealing", one can argue that Activision stole Classic from the old Blizzard devs:D Devs who cared... Start banning rmt on wow and you lose a huge amount of revenue.
The latter two points were always so much more active than in Classic... You shouldn't hate on them in case you don't know the circumstance.
I had a fantastic time playing on mywowgold pservers. Additionally, I saw the quantity of effort they put into bugfixing, core development, banning bots, overall support.
Ye, I may be idealistic, but I do believe there exist adequate people. There also exist people passionate about the game. There also exist people that are familiar with their business model who will not cheat for larger profits.