Your last paragraph makes no sense to me.

There were plenty of places which published long, complex, nuanced data and explanations about ivermectin.

But lots of people are unable to understand complex writing or statistics. And most people have little understanding of biology, medicine or disease. This led to widespread misinformation, which in turn led people to try to simplify out all the complexity, and trim it down to basic things like "ivermectin doesn't work" and "don't take horse medicine when your doctor refuses to prescribe ivermectin to you".

The messaging you think would have "prevented a lot of wasted time" was exactly the messaging in the medical reports that started the whole problem. Dumbing it down was a response to the "internet arguments".