I think law clerks and other legal professionals would be using a curated service (most likely LexisNexis) as their primary information source, not Wikipedia.

Wikipedia is quite unreliable on any major legal case, controversial issue, political personality, corporate entity etc., as the relevant wikipedia pages end up being heavily manipulated by agenda-driven editors who often erase or alter the most important information.

I would guess that google and other search engines have much better search functionality than curated services. You'd find a case via google, then review the details on a curated service.

Curated services like LexisNexis aren't necessarily free from bias either. One need not use a single service exclusively

Exactly, Wikipedia is the first step for almost every expert professional in every profession. We all do it, and the world is better for it.

Also the causality of the argument in the linked article seems clearly backwards anyway: it's not that "Getting a wikipedia page for your case makes it more likely to be cited", it's "More important/citable cases are more likely to have a wikipedia page". Which is sort of an obvious point.

The linked article is describing a randomised trial, which looks like it was set up in a way that's good enough to be sure the causality goes in the former direction.

Your second comment is incorrect.