Legitimacy when it comes to leeching?

I dont understand why people dont like leeching. I mean whats the difference between training and leeching? Leeching you are afk and training you are not. If people could afford leeching go for it. If people want to earn mesos by selling leech, thats fine too. There is nothing wrong in buying or selling leech. It isn't like your hacking or scaming or using bad language. You are just afking and people are training you. Thats it! Thats all!