

That veers into subjective territory, though. From your example, going to a vegan community and declaring that you don’t believe veganism is sustainable would be seen by most as not contributing to discussion, but just trying to troll or incite a flame war. I’d consider that detrimental and downvote.
On the other hand, asking “How can we make vegan lifestyles more sustainable?” would be something worth upvoting.
Communities are not necessarily places where people go to debate or have deep discussions, often it’s just to find solidarity and meme out with good vibes. I’m not going to go to the Elden Ring community and say “Elden Ring is trash”, even if that’s a valid opinion for someone to have, because that’s not really the right place to have that kind of discussion.
It’s a bit like making alcohol—it’s made through fermentation, but you want it to be very controlled.
Normally you’d want to sterilize the starting mix first to kill any undesired molds and bacteria, add the fermenting agent that you want (lactic acid producing bacteria in this case) and age it in a sealed container until ready.
If it starts with any contaminants or if any are introduced during fermentation, it’d spoil the batch and make you very sick if ingested.