There are two reasons you might want to use a crate, The first being that you want to use a good solid implementation that you know someone has spent more time doing and works better than almost any solution you could integrate. The second is you don't want to spend time implementing that.
Writing macros in rust is a pretty horrible experience but it's not difficult
The horrible practice is not writing libraries, it's having individual small packages like this crate that are handled by individual small authors, and ending up with huge webs of small dependencies.
The better practice is for bigger projects to form collecting such small utilities into larger utility libraries that have some organization, security practices, code reviews, etc. Good examples are Java's Apache Commons or C++'s Boost.