Macros can be very powerful. But! They are like DSLs, in that they create their own mini language that you have to learn. Arguably worse than DSLs, macros modify the context of the host language in which they are invoked. That is their power, but it's also what distinguishes them from regular library functions, whose interface semantics are generally simpler to reason about.

Macros are preferable to runtime reflection and monkey patching, but the compile-time reflection and monkey-patching represented by macros still incurs a complexity tax that needs to be weighed against the alternative of non-macro code.