Every extra unnecessary feature one uses in a solution has a multiplier impact in complexity.
Consider this in an abstract way. Think of a solution that needs to solve two problems - call them 1 and 2.
Our first designer A makes a solution which finds a way to only provide one option for problem 1 and one option for problem 2.
Our second designer B makes a solution finds a design which gives two options for each of the problems. Call it 1a and 1b and 2a and 2b.
On the face of it designer A’s system should only be half as complex as designer B’s system - right?
Well no.
The problem is that these features need to be integrated and made to work with one another. Here’s a simple visualization of this:
System B is roughly 6 times as complicated as system A.