I used to say... if Amex is not accepted at Loblaws, there's a problem with Amex. (Just taking Loblaws as an example) Now I say, you don't take my Amex... I'll bring my loyalty & business elsewhere.
If you don't take my form of payment, I will not give you any form of business! If all Amex users would do this, it would add up.
Here in Atlantic Canada, most places do take Amex even small businesses and the places that don't; Loblaws & Zellers, I just don't go there anymore. Who shops at Zellers anyway?! As for Amex customer service in general, it's great! Years ahead from the many other credit cards I had or have.