I guess my issue with the man pages is mostly that they just don’t try to be approachable to the not-so-tech-litterate folk who might be interested in Linux if we had resources that didn’t assume all this foreknowledge.

That's a fair point. Their problem is that they both have to be relatively concise and as exhaustive as possible, which makes it difficult to be user friendly. So the style is usually terse and more friendly to seasoned users than to the new ones.

I think beginning users would do well to invest in something like an introductory ORiley book rather than rely on the often highly dubious online stuff. I've seen so many absolutely atrocious "Linux for beginners" pages that I really wouldn't recommend any.

this advice would not be helpful for an openbsd system

Sorry, I wasn't aware of that. BSD usually has excellent pan man pages.

Here's the relevant section in the Linux one:

The following conventions apply to the SYNOPSIS section and can be used as a guide in other  sections.

       **bold text**          type exactly as shown.
       *italic text*        replace with appropriate argument.
       [-abc]             any or all arguments within [ ] are optional.
       -a|-b              options delimited by | cannot be used together.
       argument ...       argument is repeatable.
       [expression] ...   entire expression within [ ] is repeatable.

The destination, with or without the username to connect as, may not seem like an “argument” to a new user since it doesn’t have a dash before it like the example does

Then the new user should real the ssh manpage which very clearly specifies that it is.