Lisp is not to blame here - the community is.
A properly organized community can create standards for the use of macros to prevent their abuse and standardize on libraries to prevent fragmentation. Unfortunately, the Lisp community isn't well organized.
In other words, it's not a technical issue, it's a social issue.
Simplicity of languages can and does (in many cases) translate to complexity of programs.
There are features that complicate the language and simplify programs and vice versa.
All other mainstream languages complicate matters with operator precedence tables, multiple operator notations (prefix, infix, postfix, postcircumfix, etc), and many other syntactic weirdities.
The simplicity of the language makes it the best language there is for collaboration. Lisp is not to blame here - the community is.
A properly organized community can create standards for the use of macros to prevent their abuse and standardize on libraries to prevent fragmentation. Unfortunately, the Lisp community isn't well organized.