We do this for each rental after being stung for damage done to the vehicle after we'd returned it[1]. It's an annoying flaw in their rental model; I now take photos/video of the car after I've returned it to hopefully prevent getting the blame in a future similar scenario.
1. You're essentially liable for any damage up until the time that it is next booked out. We had to pay as there was nothing we could do to prove it wasn't us. That damage even includes things like "damage caused by unavoidable events such as floods, hail, wind, trees falling, etc."
This personal choice has its issues, sure, but I have been happy for 7+ years this way, and aside from the one time I tried to rent a car at SFO to take for a weekend getaway, it has never been a detriment to my lifestyle.
BofA at least already does this - https://www.bankofamerica.com/privacy/accounts-cards/shopsaf... ..and a better frontend to it would be great!
https://www.citibank.com/us/cards/gen-content/messages/van/i...
You are only doing yourself a disservice by not getting a credit card. I get purchase protection, price matching, fraud protection, free extended warranties, etc, for free, from my credit card provider. That's a pretty good deal.
A credit card isn't a ton of protection for the rental car company anyways, regardless of authorization it's not likely you have a credit line to cover the entire car.