Why is there a difference in the character limit for VARCHAR2 in SQL and PL/SQL?

While working with some large scripts I encountered errors related with the 4000 character limit that VARCHAR2 has in SQL but not in PL/SQL.

As explained here the VARCHAR2 datatype has a 4000 character limited, while the PL/SQL has a much larger limit of 32,767.

Why does that difference exist? Wouldn't have been better to have both VARCHAR2 with the same limit? It seems a rather confusing and prone to error decision.