Hari I see you are very obsessed with SEO but I think you are missing the point here, because you are getting frustrated with things that don't even make much sense, we are talking about internal links and from what I have seen on popular sites this technique is not used either... is it even necessary?
If discussion has 10 replies flarum is telling not to crwal those posts by mentioning nofollow tag
This is not true and you probably already know, why any bot would crawl an internal page through a post when they can do it directly from the source? it is not optimal and rarely happen even less with a sitemap.xml, you can do it no doubt, but I think it is obvious that the internal links have already been crawled, because otherwise I don't even know how the user has reached your page.
Honestly I don't understand the obsession of some people with SEO I mean, the relevance of the content and the speed of the site is the most important thing to be well positioned, that your forum does not appear next to the results of Reddit or Quora is not a question of technical SEO, I can tell you the example of https://forum.webdeveloper.com/, I've run into that Flarum forum in completely random searches on Google lots of times... how do you explain that then? although all the technical SEO is fine the complexity of the search engine algorithms are not that simple to get their attention and the bots are not that dumb either, there are lots of factors mostly non-public for each engine, that's why also the searches vary so much between search engines.
When Flarum's SEO issues are fixed you will probably be surprised how little effect they have on your site's ranking, but you will see that in the future, obviously it will be addressed at some point, but to me it doesn't seem so critical, in fact any improvement in Flarum's performance would have better effects on SEO than any rel attribute.
