Sometimes endowing existing syntax with richer semantics requires almost no documentation because things "just work". For example, cligen [1] uses a macro to synthesize an argv parser -> call dispatch CLI system. It could almost have been a template but it needs to loop over parameters more than once (and then grew a lot of features).
Anyway, since Nim has user-defined new operators, using those might also bother some. E.g., there could be a proc `=>` meaning something very different from that sugar module macro of the same name. Really, these work just like other procs modularity-wise. The syntax/grammar does not actually change, though. It's just flexible in the first place.
These complaints sound more like excuses to me. Every language has calls, styles, idioms, etc. you need to learn as a client of whatever it is you're calling/doing. And every language has quirky syntax corners. E.g., many are unaware that C lets you say "(a,b,c,d)" { which evaluates but ignores the result of "a,b,c" }. Yet you still often hear people proclaim how simple C syntax is. "Compared to what?", I guess (e.g. C++).
I do get where you are coming from "overloading"-wise - not just operators, but also regular procs (which in Nim are the same...there is just a proc `<`). When learning an alien language/code-base/libraries it really helps to have jump-to-definition. Nim via nimsuggest has great support for this if you configure your editor (vim, emacs, VisualStudio Code, etc.). You may have skipped that step but might love it more if you did it next time. nimsuggest can be aware of local and global --path modifications and the type context of the jump-to-definition. So, it can do a much better job than, say, ctags. (and yes, nimsuggest works for all the various definition types like macros, templates, etc., even the ones named like an operator such as `<`).
[1] https://github.com/c-blake/cligen
