As noted, when it goes away, people always look to what they did, to get rid of it - and it might have been something else, or nothing. I've been in the hobby for over 35 years. Here are MY experiences:

The article is pretty much right on, based on my experiences.

I DON'T quarantine. Basically because it's pretty much SO difficult to do, and stressful on the fish. Logistically, it's very, very difficult to do.

I also don't FW dip, put chemicals in my tank, raise or lower the temp or salinity, or use UV. I HAVE a UV sterilizer, but don't use it because it will never get ALL of the parasites - and only affects the free floating ones. Why bother?

When I have an occasional outbreak of Ich, I just make sure the water is good, and they are well fed. It's ALWAYS because of stress from a new introduction, or a tank rearrangement.