No bank will give you anything on an empty promise
They will, though.
Sure, things like mortgages or car finance are collateralized against the value of your home or your car, but lots of loans aren't. I could get a brand new credit card today with a five figure spending limit, based solely on my past behavior, and without providing any collateral
This is definitely not an empty promise
But you wouldn't really expect a random dude from the streets to get a five figure credit on his word alone, would you? Also, a five figure amount can be anything from 10k to 100k and in what currency exactly? Regardless, how many people are willing to lend coins here to a fresh account? I don't think that many if any at all. So why should banks be different? Anyway, the loans you are talking about won't make a dent in the bank's balance if the borrower defaults on his debt, so my point still holds overall
Starts ups looking for business loans often have little in the way of collateral to provide. Sure, the bank could come after you for damages if you default, but that's not the same as them having assets to back up the loans they provide
Startups are typically looking for venture capital, not bank credits
The entire modern banking system is based on the fact banks can create money without having the assets to back it up
Okay, let's agree to disagree here