Not sure what that has to do with Lisp then, since macros establish conventions, but on a language level. Example: the Common Lisp Object System was initially

Not sure what that has to do with Lisp then, since macros establish conventions, but on a language level. Example: the Common Lisp Object System was initially developed as new a library, based on two other earlier libraries. This was then standardized and it is the standard way to develop object-oriented software in CL. The library has three API layers: an object-oriented layer, a functional layer and a syntactic layer. The syntactic layer is implemented with Macros. It provides for the developer a convenient way to specify the elements of an object-oriented program: classes, generic functions, methods, control structures, ... As a developer everyone prefers to use the syntactic level. There are many libraries and applications using it. It's also extensible, so that other user can add new behaviour to the object-system itself. That macros enable new language extensions also on a syntactic level is nothing special. To use macros from other developers is not more difficult than using a class graph, or similar. There is a lot of 'fear' of user-level syntax extensions from people who have never developed with it. Understanding the implementation of macros themselves is an added burden, since many developers are not used to write&read code which is written on a meta-level of incremental code generation. But there are practices which can be learned and applied. Macros themselves can make the code much more readable, since it allows one to support a problem domain also on a syntax level and hides implementation details.