The set of unique and special needs follows a power law: you are going to get most of the benefits from a small set of very common commands. The long tail will be rarely used.

Under a reasonable assumption that 'brain space' is finite, not filling it up with editor commands that may be used at most once a month will leave room for something more valuable instead. This applies for many other aspects in the life of an engineer: indiscriminately memorizing the options of ps/ls, specific APIs, etc.