I'm not really bothered by it, if someone wants to buy or sell a run. It's of no mind to me. However this is a case of the community being its own worst enemy. I know how having someone who bought a run can be a detriment to the party. I can't really blame people for buying clear runs though when I see comments on patch day just an hour or two after server up of party finder messages of "must know the mechanics perfectly or kick" or walls of text of whatever bad things the leader wants to do to you if the party fails. Mixed with comments of "this content is a week old, what do you mean you haven't done it yet??" If a new player misses the server up learning time, isn't fortunate to be able to play that day or wants to do it later. Said player often get's chastized for missing the boat. I know not everyone in the community are jerks, but when faced with jerks over and over its easy to see why run sales are popular and why people turn to them.
After all, which case means a new player would at least get a chance to see and try to learn the mechanics. Buy a run, or get in a fresh instance where the party disbands the second they see the new player bonus?