* mapping resources to reality: your instance "bob-7" is actually "i-12bc50812ab2", there are lots of circumstances where what you declare has to be matched to

* mapping resources to reality: your instance "bob-7" is actually "i-12bc50812ab2", there are lots of circumstances where what you declare has to be matched to something that exists because the model of the resource just doesn't match what you can declare * drift: terraform can tell you when something you created but didn't specify has changed (there are often a very large number of parameters you don't necessarily want to specify each one) * speed: there are a lot of things that could be looked up but doing so is slow and APIs have rate limits. wouldn't it be great if all the providers had fast apis that allowed us all to do all these things? sure. but we don't have that sometimes for technical reasons sometimes just because teams don't bother sometimes because the architecture of solutions would have to be very fundamentally changed in order to make them fast