The use of the word congregations is a bit overly used, better would to haved use organized
associations, such as a dozen people or less.
History gets re-written each time a religion "clarifies" its past, and that's not always prompted by a desire to fudge matters either.
Keep in mind, the word "congregation" only came into widespread use among the JWs in the 1950s. Before that, kingdom halls comprised "companies" of witnesses rather than congregations. Literally speaking, even home meetings could count as "congregations" because the word simply refers to groups of believers meeting at the same place. Whether there's two, three individuals in those "congregations" matters not.
I do not think that the Watchtower's accounts of how many "congregations" there were at that specified time (1918) is deliberately inflated or designed to create the impression of greater attendance. As I said in my previous post in this thread, the composition of the "companies" of Bible Students (or, if you prefer congregations of Bible Students) was radically different from what it was to become during Rutherford's "reign" which, in turn, gave way to other permutations of "memberhip".