Isn't the point of the article that you need less tooling with monorepos, not more (examples given: cross-repo changes, code searching, git bisect, dependency management).

Now, you might be referring to the fact that Facebook and Google have built up lots of tooling to help git/hg scale since their repos are too large and operations take too long. But that is not a problem you're going to have until you have at least a thousand engineers. At that size you need tooling for everything anyways.