The blame is pretty one-sided here.
The U.S. has been going off on its own cockamamy missions to procure oil for the past 10+ years, expecting NATO to help or clean up the mess. The only mission I agree with is Afghanistan. The rest are U.S. vendettas that the other nations should have no part of.
If the U.S. pulls out of NATO then it's because the U.S. wants to, not because other countries aren't doing their jobs.