As a business owner I can tell you that customer fraud is Rampant and they often use chargebacks and threats of chargebacks to get free stuff. Some customers game the system so badly that it is likely they pay for almost nothing they order online.
The cost, of course, is passed on to the honest customers. That is the only way a business can stay in business.
By putting the onus on the customer to do due diligence and only trade with reputable businesses, the way is much more clear. Reputable businesses work with you to solve problems that may arise. With bitcoin they do not have heavy handed credit card companies who profit from chargebacks and give customers free reign to commit fraud.
Consider this: is a 10 Million dollar company going to try and cheat you on a $20 item? No. If they do they won't be in business very long as word of mouth is #1. In addition, that is alot of work in order just to make a couple bucks. They just don't do it and its simply not worth their time and effort.
Would a customer try to cheat a 10 Million dollar company out of a $20 item? Yes. Many hundreds do as a matter of course.
My humble opinion based on real world experience. Your results / beliefs may vary but I believe that if we eliminate the chargeback customer fraud problem then prices will fall for all of us honest people in the long run.
Yes, it happens.
PayPal is an all to familiar realm for customers to scam eBay sellers by claiming they received damaged or fake items.
Some people will complain about anything for a freebie.
I've found credit card companies to usually be fair in the chargeback process from a business owners point of view. But there will be always those who are there to game the system from the start and pull crap unfortunately.