Well known types strike an interesting balance between IDL and compiler simplicity vs ergonomics. For example maps were added in proto3. They use the same bina

Well known types strike an interesting balance between IDL and compiler simplicity vs ergonomics. For example maps were added in proto3. They use the same binary encoding as the proto2 pattern that you could use to implement mappings (repeated field of key value pair messages). Adding maps as first class citizen in the IDL dealt with the lack of type parameters that would have been needed to implement a Map well-known type.