Teaching calculus to children is a good example of why. They have a teacher to hold their hands and answer questions 40 minutes a day with mandatory homework assignments.
If you study concepts on your own, you do not have this luxury. Its very difficult to internalize notation when you do not use it every day. The problem is not the notation itself, but the fact that no notation can be categorically searched and referenced. It cannot be typed or entered into google easily. It is rarely consistent between authors, which is free of problems if you are already fluent in the notation.
Sometimes you can get away with "what does upside down A mean" but consider something like `\forall n \in \mathbb{N}`. Imagine if you simply had `unsigned int` (I don't want to debate the exact implication of unsigned int versus the naturals, but it should serve a point).
When I have tried to explain relatively simple notational structures to working engineers, the universal feedback is along the lines of "I wish there was a good reference for notation because I can't understand this or keep up with it."
Pseudo code, or something akin to it, may be more ambiguous but is much easier to grok and document.
As an aside: something that constantly irks me is the celebration of terseness and convenience. This plagues many texts and robs novices and experts alike from understanding. Notation that is terse to the point of resembling arcane incantations is a problem, and it bothers me that academic publications in the applied sciences don't recognize it as one.