How would you like it if you asked "Can I mount my electrical outlet upside down?" And my answer was
Yes, if and only if you comply with NEC 216.15 Note 3.
And then you're like "WTH, why should I have to spend $125 on a copy of the Electrical Code?"
And we say "Because it's an essential resource for anyone doing electrical work."
And you say "I am changing a fracking outlet."
You'd be right. Just because someone wants to flip an outlet, doesn't mean they want to design sitewide wiring for a refinery, which is what NEC is mainly for. It's perfectly easy to write answers they don't need the book to understand.
Inclusivity is the biggest reason
These are the meta-messages we would send. "This is a closed club. Pay the club dues, OR GET OUT." There are bona-fide reasons why some people shouldn't do DIY home repairs, but "possession of a secret decoder ring" is not one of them.
Even when ThreePhaseEel and I are having arcane discussions about the fine points of Rapid Shutdown (render-safe for solar panels so firemen don't get shocked, see how I told you what it was instead of excluding you?), we still use our Fair Use rights to quote the relevant snippets for all to see.
So we have the option of making our forum very hostile to folks just entering home repair, or keep people out of the deep insider conversations we are having... and we make a point not to. And nobody told us to do that. Why? Hmm, I suppose because our core drive is to share our passion.
...Although there's also a big problem with obsolescence
That's an SE-wide policy, and it's for two reasons.
First, obviously, is link rot. We too can link the official NEC site, however the site can change their layout anytime they want. And my experience is that webmasters reorganize content at least as often as they change platforms, and only about 5% of them support old links after a reorganization. So there you go, d20 lol. The problem is, if you don't roll a natural 20, every link on the stack breaks at once. It becomes totally impracticable to hand-edit every one, and nobody ever bothers to write an automator. Which you'd have to run everytime, and that's often not even possible even if you do build it.
Second, the rules change. You're going "There is no NEC 216!" Yeah, whoopsadaisy, they removed that rule. Nevvermind! And as you certainly know, in D&D, the rules change a lot.
Recommendation: Quote and cite
Certainly, quote the essential snippets of text. This is allowed under the Fair Use doctrine of copyright law, in fact, it's an open-and-shut case. When you quote a section, definitely attribute it, of course, with a reference to the content (version # and findable reference point ideal, e.g. "NEC 310.15" or "5E MM under displacer beast"; URL to dndbeyond secondary).