I was working with one crawler, to be used by MoodleBot, and the first page that I tried was https://moodle.org (how not! )

Surprisingly, the crawler found that page empty (not having any meaningful/main content).

Looking a bit to the HTML contents, it seems that we are inserting everything there using the standard Moodle blocks feature in the main/central/content area. Sort of replacing the real "main" content that remains empty.

And, generally speaking, the main content of a page should be into <main>, or <section> or many other tags, but not in <aside> blocks that are used for secondary, complimentary, extra information.

Then I went to moodle codebase and, more surprising yet, it seems that the code in charge of rendering the blocks is already clever and when it detects that some block is going to be output in the content area, the <aside> (incorrect for that purpose) tags are replaced by <section> (correct) tags.

See the last lines of this code, the replacement should be happening there.

But that replacement apparently is not happening for moodle.org and the <aside> tags remain there, and crawlers (and maybe other tools too, say accessibility ones), by default, may ignore them completely.

I don't know if that is because of the use of a custom theme, or a custom renderer, or how the moodle.org front page is being built, but for sure, the current internal structure doesn't make much sense.

And that's what I've found, so far. In theory that page (and other, similarly built ones), should have a better structure, specifically avoiding the use of <aside> tags for the main content.

Ciao