It seems to happen for most things online. It's probably many things about online discourse that make it so, but for hobbies it's probably because you have super passionate people, and people who are too busy being online to have actually done much of the thing, talking with identical authority on the topic. That leaves the median people drowned out, if they're online at all.
This is a paradox of modern life, where we're indundated with gear choices and advice. Any nontrivial activity can be approached in a minimalist or maximalist fashion, and there's no certain way to choose one over the other. It doesn't require the Internet, though it may be influenced. Just mention home cooking at the lunch table, to experience the full brunt of it.
Even the minimalists brag about their (remaining) stuff, which always includes at least one Apple product.
The in-between-alists just smile and nod, knowing that we'll be drowned out.
Another facet of modern life is being able to try everything once, which means having to get the most out of it, with the assurance that it will be great. Heaven forbid figuring out your gear needs on a progression of increasingly ambitious outings, some of which are miserable. This is how we end up with beginners on extreme hiking adventures.
The incremental chances of dying from hiking in jeans are probably small, but those of having a bad time are non-negligible (and I say that as somebody who’s hiked quite a bit in jeans due to not knowing better). And why would you want to have a bad time?
It doesn’t need to be high tech activewear: Running shorts (weather permitting) can do just fine.
Getting into the weeds here, but being inexperienced in the outdoors and in running shorts vs jeans in North America could easily result in Lyme disease
The moral: know everything I do and be safe in the way I find acceptable
Everything you do must follow the exact best practices and maximum safety protocols
Someone in this very thread is saying OP could die from wearing jeans hiking
Its honestly ridiculous the exaggeration that goes on in internet hobby forums
And the risk acceptance is arbitrary anyway
You can argue that wearing jeans hiking is taking a risk
Then I can 1-up and ask why don't you wear a full 1-piece high-vis yellow suit and wear a helmet at all times whenever you leave your house?
You could get hit by a car?
Why would you take that risk?