To say that the card selling sites are failing across the board is pretty extreme. I've had almost no problems with sportlots, ebay, dacardworld, blowout, COMC, etc. The current delays for COMC are crazy but I have excersized my option to stay away from them until they get their shipping caught up.
I've bought over 2000 things online over the past 20 years and have only had 4 things fail to arrive. 3 of those were 10+ years ago and I ate the cost, 1 was more recent and I got a prompt refund even though they shipped it, it got scanned in and then proceeded to bounce across a few states before getting lost.