It's the jargon, I think. PL research is in an awkward position, where the jargon is not shared with the much wider community of people using programming languages daily. From the other side, it looks like there is a small body of theoreticians using impenetrable language for discussing topics I'm supposed to be familiar with, because they are a core part of my day job. It's much easier to accept jargon, when it's used in a clearly separate field.

Some of the terminology is just unfortunate. For example, I have an intuitive understanding of what a type means. The meaning used in PL theory is somehow wider, but I don't really understand how.

And then there is my pet peeve: side effect. Those should be effects instead, because they largely define the observable behavior of the program. Computation, on the other hand, is a side effect, to the extent it doesn't affect the observable behavior.

But then PL theory is using "effect" for something completely different. I don't know what exactly, but clearly not something I would consider an effect.