If you’re talking about generating a nice preview after pasting a link, yes, you’re right.
Every website has specificities, such as different formats, modes, URL structure, etc.
It’s not always as straightforward as wrapping the URL inside an <iframe> directly.
If Onebox doesn’t work with your site, this means no one requested it before, feel free to do so.
Alternatively, you can still insert an <iframe> of any site directly into a post if you whitelist the source.
