I understand people are weary of scams, but I'm not sure how this applies. Several people are doing group buys priced in USD via paypal. If someone was to attempt a chargeback, they would simply remove them from the shareholders list. I have been around the forum for a few months now and have made numerous posts in various subforums.
The reason why I want to pay in USD not btc is simply I do not have enough btc to participate in these group buys. I don't want to use an exchange like Mt Gox or BTC-e because they seem shady to me. Until an exchange offers low cost, fast transactions, via bank transfer for any amount then I would be willing to use it. I am not going to pay 3% to person X wait a week pay some more fee's etc.
Also I believe paypal has the option to pay as "friends or family" which cuts fees and possibly protects against chargebacks.
coinbase is instant with low fees after you get stage 2 verified. Also the price is not tied to Mt Gox nor btc-e