Re: One problem cancels all accounts with same credit card issuer?
+1 to what others have said. Its best to just diversify, especially if you engage in any sort of manufactured spending.
Whenever your relationship with the bank goes south for any reason, regardless of whether its due to manufactured spending, suspected fraudulent activities / claims, late payments, risk issues, etc, there's always a risk that they will close all accounts and possibly blacklist you in extreme circumstances.
Unless you are okay with doing away with credit entirely and able to survive on a cash / debit basis, its best to have a few other banking relationships as backup.
JPMorgan Palladium (100k), AmEx Platinum (NPSL), AmEx SPG (46k), AmEx BCP (42k), Chase Sapphire Preferred (47k), Citi Prestige (31k), Citi Thank You Preferred (27k), Citi Executive AAdvantage (25k), JPMorgan Ritz-Carlton (21k), Merrill+ (15k), US Bank Cash+ (22.5k), Wells Fargo (12k), Bloomingdale’s (12.4k), Chase Freedom (5k), Discover IT (5k).