Ivmmeta:
1. Communicates clearly.
2. Has a simple pitch (look at all this evidence! here are links and all the details we can find!).
If you are evidence based you have to admit ivmmeta.com is interesting (it compares extremely well to the usual tripe for ordinary people which typically just reports "studies show..." with no links or sources - or like this article, one study in a sea of conflicting and complicated studies). If only the governments of the world had the resource of Big Ivermectin and could summarise data effectively and present it as one would to an adult. Might even work better than mandates and threats, what do I know.
The counterarguments tend to be vague. When this post says "various research studies" - links. Specifics. Names. This is something ivmmeta has that the post doesn't. And that is why ivmmeta is more persuasive communication.
And as far as I can tell, based on the geographic distributions, ivmmeta probably is reporting on a real effect. That helps the argument that they are just good communicators rather than malicious.
PS - fun anecdote, a close family member of mine was diagnosed with threadworms around the time they got their 3rd vaccine shot. Ironically, assuming Ivermectin works on threadworms, they might have had better chances with COVID if they'd taken Ivermectin at the same time as their shot.
PPS - If there is an ivmmeta equivalent for vaccines people should throw it around more. It is difficult to figure out how effective they actually are given the waning of shots and complexity of cross-country policy comparisons.