Because the creditors make money off it as well.
They are other banks, and probably all the suppliers who give to NM on credit and who won't get paid.
Chapter 11 is by default bad news for creditors, it means they will get less than the agreed-to value of whatever.
Depending on their status (e.g. if their debt is secured by a lien), it's totally possible that some classes of creditors could be reinstated with the same claims under the reorganization plan (assuming it gets confirmed by the court). Even if a secured class doesn't get the same value and votes against the plan, they're still entitled to a handful of protections under the Bankruptcy Code (§ 1129(b)(2)(A)). Less so for unsecured creditors and shareholders.