Answer to https://stackoverflow.com/questions/57688166/

answer_to_57688166.md

The only reason is to make it easier to embed them into the pipeline built with Kernal.|>/2.

As one might easily see, String.replace/4 delegates to Regex.replace/4.

When one starts with a string, they might pipe String.replace/4 without a necessity to leave a pipeline. When one starts with a regex, the same applies to Regex.replace/4.