I guess the bank has the property as collateral. But liquidating the property is also expensive and risky. Generally if you want people to borrow money from you, you want those loans paid back with interest. It can't help business to have customers constantly defaulting and leaving you with physical assets and costly legal and liquidation proceedings.
The other thing the article mentioned was "credit tenants": big chains that will take out long leases and continue to rent even if they close the location and it appears vacant. But while clearly the banks would love these tenants, there wasn't a connection made in the article between "borrower is about to default because they can't find a tenant" and "credit tenant swoops in to save the borrower and bank." The only thing credit tenants seem to add to the story is that they are yet another reason there are so many vacant retail locations. A big chain opens a store, and then closes it because the under-performing location costs less to run out the lease than it does to keep it operating.
I'm clearly missing something.