- Amazon, doesn't have a very understanding attitude when sellers don't manage their inventory well. If you have to refund too many orders, because of stock outs, or you get too many negs because of the bad experience, Amazon will suspend your account and once suspended it is difficult to get back in.
- eBay is now cracking down on sellers who have these types of problems also and while you may not be kicked off the site for less than stellar performance, you will get disadvantaged in search.
This does limit the long-tail product, especially in the media category, but if a high percentage of those items have inventory problems, what good is it to sell them. Consider the downside to listing those items, just to get the incremental sale.
If you sell on multiple platforms, you need to develop a strategy for your inventory. For example Amazon usually has a huge Christmas, while eBay does real well, but this year that is in question. Identify which items sell best in which marketplace and adjust your inventory to get the most bang for your buck. Do not list the same inventory on multiple marketplaces unless there is sufficient quantity.
This year more than ever before, poor inventory management, may have a real downside for your business.
Just my 15%