I see your point, I think you may downvoted because you did not elaborate rather than just say "you're wrong".

Let me see if I can elaborate on what I think you mean. Homoiconic can be interpreted as meaning that the programs structure is similar to it's internal representation and so then it can be argued that an argument list is implemented as a vector and so should be represented as such.

But I would suggestion that this is an implementation detail and would hazard that many Lisp implementation might share this implementation strategy. I suppose I should have described it as something along the lines of needlessly breaking with Lisp syntax traditions.

As an aside the reader macros themselves are not the problem as lists are not a one size fits all data structure within current computing so there is a need for vectors and hash maps etc.