It is different for each game, typically boosting or carrying people for free is not against any rules, mainly because there really isnt any way to prove this. However for many games payed boosting is not allowed. This can include anything from selling/buying accounts, to buying/selling carries through activities (both multiplayer and campaign). I know that games like league of legends and world of warcraft will ban those that buy/sell accounts, if they can find evidence of the sale/purchase. Games like destiny have it written in their code of conduct that you cannot sell or buy services in the game (carries), but as far as i know they haven't enforced this rule. Most companies just put these rules in for legal reasons, if they say thst real money trades are not allowed then they are not responsible when something goes wrong. As for the question of should it be allowed, i person really dont care. I dont think companies should chage their codes of conduct because it makes perfect sense for them to protect themselves from others peoples decisions. But i really dont care if people want to buy accounts or carries. If people are just that bad at a game or just want to spend a fair amount of money to save time then so be it. It really doesnt effect my gameplay. Some people get mad at those offering to carry people for money, but again i dont really see the problem, it doesnt harm me and if people are willing to pay them then go ahead. I wont be paying anyone for a carry, and i will continue to offer people help without asking for money, but that is me and my decision, and so long as people leave me to my decision then i will leave people to their decision.