Can anybody explain why? And what's acceptance criteria of the list?
Maybe they set some kind of fee like exchanges do so those who can afford to pay that fee are able to list their coin. Top coins like Bitcoin, Ethereum, Litecoin etc are listed as a default as they are listed everywhere.
Even if you are the one who owns the business you will also choose few coins to allow on payment. you will have the coins you believe that you can hold for a long time and make the profit from it aside from your business products. if you will accept every coin that will throw to you, you will have a problem as people will just pay the dropping coins to you and keep holding the potentials.