What would a keyboard user who doesn't use Assistive Tech do?
I personally think this is just poorly worded and is trying to say that it offers an alternative way to navigate for Assistive Tech that doesn't intrude on normal operations (as screen reader users for example rarely use Tab and are more likely to navigate my sections or headings and then by links...which would catch skip links obviously).
If all else fails or advice seems to conflict, you should always follow advice in WCAG over WAI-ARIA spec anyway and WCAG is pretty clear that skip links are a level A requirement.
And if you still aren't sure - go user experience over guidance and compliance every time!
Skip links offer a much better user experience to keyboard only users without assistive tech and have very little impact on screen reader users so use them.
As a final note on this - it is 2021 - unless you are supporting IE8 or older (and even I don't advocate for that sort of madness!) you shouldn't need role="main"
and instead just use a <main>
element.