Combinatorics is a field in maths, therefore by extension it is a difficult and respected field. Indeed, a field develops very quickly until it becomes hard for humans, so a field in math is almost certainly hard. Many schools don't teach a specialized class in many different specialist fields.

Is combinatorics the hardest math?

Combinatorics is perhaps most simply defined as the science of counting. ... Combinatorics is, arguably, the most difficult subject in mathematics, which some attribute to the fact that it deals with discrete phenomena as opposed to continuous phenomena, the latter being usually more regular and well behaved.

Why is combinatorics so difficult?

In short, combinatorics is difficult because there is no easy, ready-made algorithm for counting things fast. You need to identify patterns/regularities offered by the particular problem at hand, and exploit them in a clever way to break down the big counting problem into smaller counting problems.