i think its more that people are just upset that airlines dont allow buying and sellling miles and will shut you down if they catch you. although i think BA might be one of the stricter airlines (or just better at catching people)
Disagree with you.
People are upset on "the way" they shut down accounts.
AA even if they are considered the most aggressive airline, they make sure you are fully aware of the process, and will give you a deadline till when you can respond etc...
Vs. BA that in most cases will not even notify that it was shut down, just come the airport and find out. This is not an option, only if the airline is 1000% sure that this was a sale. But how could the airline be sure, they can only guess, and so they MUST be in touch beforehand to verify this. And this is why people are angry on them, and same is to UA.