I do take in your qualifier referring to degrees of consumption.
Everything in the world is toxic. There's no such thing as a safe substance. Too much water will kill, too much oxygen will kill, too much of anything will kill. Some substances will kill some people while saving the life of another. All the absolutes about what's good and what's bad for us are often at best misleading.
It's more than a qualifier, it pretty much defines what 'toxic' refers to.
This clash/mixing is common in many situations, causing confusion.
It's usually quite simple - those who believe they know, often because it's something they've taken an interest in previously and leant more about it, are correcting what come across as clear misunderstandings.
All our discussions on this site (bar some rare one's I'm unaware of) are general/layman discussions.
To have a proper professional/scientific discussion we'd all need to be professional scientists (or equivalent) working in the same or related area's.
But some of us are particularly taken by scientific methodologies, and what science represents, even so far as to be as much a philosophy as anything (e.g. the importance of evidence). So just as you may correct me on some matter of art, music, literature, entertainment, theology, philosophy (etc) wherever you're interests/talents lie and reveal my ignorance and I'd have to accept that correction, but so I would do likewise to you in my sphere's of interest, without pre-judging you as a person.
From my side, and I suspect others here who do similar, it's got nothing to do with dissin' the person who has those misunderstandings, it's to do with a problem seeing a mistake and
not correcting it. For me it's frankly disturbing seeing things like that, at a fundamental level it's anathema to me and limits engaging in the conversation.
Challenging these things is also an important part of learning things. Sometimes I'll challenge a statement, and be torn off a strip because I'd missed something and took an incorrect understanding. That can be a little 'ouch' when you think you knew it all, but it's also a correction of an error, one less mistake to make next time.
Ignorance is an essential part of knowledge and wisdom. Without ignorance we can learn nothing, without accepting our ignorance, we close ourselves to new knowledge. It's important to not take the word 'ignorant' as being a bad thing, life is about choosing what things to remain ignorant of, and what things to learn more about, because no-one can know everything. The very worse thing imaginable could well be omniscience.
Some philosophies state that the more one knows the less they can know (not just in the obvious sense of running out of things to learn), and too much knowledge can also blind us to other truths. But to reject it out of hand and without thought is an awful waste. To reject it because one doesn't wish to know about something is fair enough, but it terminates the conversation regards that topic.