> What are things that are hard to do in Go business applications that other languages do better?

Streams, meta-programming, enums, ‶modern″ switches, generators, portable types in CGo, streamlined error handling, safer concurrency primitives, nil, partial struct initialization, ...

Here is an example. Go let’s structs be passed by value or by reference. The programmer needs to decide, and that adds complexity that is largely irrelevant for modeling complex business logic. Java does not provide a choice, which keeps it simple.

It lacks modeling capability that you'd find even in languages like Java and C#. Enums, records, pattern matching, switch expressions, and yes even inheritance where it makes sense.

Lacks expressivity is likely what parent meant.