If there has been over-enthusiastic use of reader macros, I think we will have to admit that the over-enthusiastic developer is no longer writing Common Lisp code.

Those reader macros have morphed the language into a new bespoke language. So it is then natural for a new developer to face a steep learning curve to learn that new bespoke language before they can make sense of the code.

I'm not condoning overuse of macros. I'd hate to be working with such code too. I'm only stating that Common Lisp is that language that can be programmed to become a different language. They call it a "programmable programming language" for a reason.