I don't disagree with you, but it's also true that you don't have to go all-in. I run services that run server-ful-ly on EC2, while requests to the "front-end" are handled by Lambda. If you've got one or two very hot endpoints and the majority of your server load spike is thanks to the processing for those endpoints, moving just those endpoints to Lambda could give you reassurance that you don't have all of your eggs in one basket (not having to go full-serverless) while also getting the benefit of being able to scale up and down essentially effortlessly.
Of course, there are lots of other consideration that you should be making when going even partially serverless, and it could be that the NYT chose not to experiment with Lambda for other reasons. For instance, you're effectively tied to CloudWatch for logging and monitoring, which could be a deal-breaker. Much of the processing could be happening in the DB, which would make Lambda moot. It may simply be that their estimated usage of Lambda was too costly.
AWS charges by hour. Google by minute. If your peak traffic only last a few minutes, hourly billing is inflexible, simple as that.