Whether they could make more profit off this probably factors for some people but on the whole the medical profession is result driven.
Also let's accurately represent what the article is saying:
"Again and again, more people are surviving (or avoiding complications) when they get the drug. It’s a pattern strong enough to common-sensically notice. But there isn’t an undeniable, unbreachable fortress of evidence."
This to me reads consistent with "ivermectin has a reasonably good chance of working a little bit but it isn't conclusive.", which is in contrast to your statement that thinking ivermectin works is equal to quackery.
Personally I think it's either a very small effect or no effect at all, but I don't think the quackery designation fits for people who simply believe that there's some small benefit there (although I do think that label fits for those that think it can replace vaccines)
And that's exactly how it goes.
Quackery: "dishonest practices and claims to have special knowledge and skill in some field, typically medicine."
You don't have the knowledge, you don't have the skill, so don't go around giving advice about non-proven cures (or in fact, about any cures).