Looks like no-one answered this question, but I’ll have a go!
Serverless framework, in my opinion, has the following purposes:
Simplifies the creation of AWS resources related to Lambda functions using infrastructure-as-code (e.g. API GW, event handling) - it is significantly more succint and easier to read than standard CloudFormation scripts. It build quite a lot of the “bolier-plate” AWS resources that you would otherwise have to create by hand.
Provides a useful libary for plug-ins and extensions that save you from having to create common deployment tools and patterns from scratch
Simplifies parameter and variable handling inside Serverless scripts compared to CloudFormation.
I would say that Serverless offers some advantages for creating CloudFormation resources, even if you don’t use any Lambda functions at all, although in this case, much of the serverless.yml would be identical to a CloudFormation script to do the same thing.