Thanks, that's a good point. It depends on your data platform architecture. Many DWH solutions support nested fields and JSON format so no need to do it. Just load the whole JSON object into a JSON column. ELT would be a way to go here because processing deeply nested JSON might be expensive if we are talking about big data. Always consumes a lot of memory and ETL microservice might end up with errors. More about architectures in my story here:

https://medium.com/p/f255ac6e0b7