Posted By:
warshawlawIt is a confidence factor. There is a big premium that people like me will pay not to waste time and energy examining and returning (if I can even return them) subpar cards. I had abandoned mail order entirely for a number of years because of the constant flow of overgraded crap that I had to haul to the Post Office to send back on my dime. Having a grade assigned by a reputable 3rd party service is a very strong (no, not perfect, but what is besides me 
) indicator that you will get what you paid for.
Although it was not originally conceived as an internet tool or auction tool, slabbing is a perfect match with buying and selling over the net or through an auction. For example, I am working on several high grade boxing sets. When I buy the cards raw I am invariably taken by at least one grade, unless I can put my hands on them in person and examine them. I have bought hundreds of slabbed cards for my sets and can count the number of disappointments on one hand (interestingly, all of the duds were PSA graded...).