Teams that have (only fairly recently) discovered AWS lets them escape the snail's pace of getting something into production within Enterprise IT, their little walled garden that IT has siloed them into (for their own good). They just absolutely love Node + Lambda because servers are scary (they tend not to have CLI skills to even CD / LS around the VFS) and it lets them get things done -- which is all their superiors value.
Places where IT doesn't value time to market, and nobody values maintenance or costs (we regularly have products owned by failing to apply patches to products using OSS, we rack up AWS bills by leaving manually created test resources around for months or ramping up products like Lambda to the moon for a batch job then forgetting to turn it back down once it finishes).