These are dubious arguments, at best. They are all predicated on the premise that you, the smart, relatively prosperous, well-employed customer (if you aren't, you shouldn't be in that store in the first place) don't pay your credit-card bills in full every month. If you are in that habit, all four of his 'reasons' are bogus.
Also, grace periods are getting very short, less than 20 days. If you travel or have bad mail service then you may pay late through no real fault of your own.