Well … if you didn’t need to hit TL3 to post even something so simple as a link, people probably wouldn’t even care.
As it is, it actually can interfere with discussion, especially if you actually want to specifically cite information about e.g. historical raiding.
I ran into this when I tried to explain the likely effects of 5.0/5.2’s difficulty on the future of the game community and couldn’t include an actual link to Tier 14 wowprogress activity.
And that’s wowprogress, a site that people easily know about without a link and can be readily directed on where to look up the cited information. Data cited somewhere like MMO-Champion gets worse, and it’s worse still if you have to tell someone to search (because unless it happens to be on a well-SEO’d site - which with a few exceptions mainly REALLY MAJOR established sites tend to have an increasingly inverse relationship with “the information is actually useful”) something, because it’s a complete toss-up if (especially with personally-tailored algorithms) they’ll even find it.
Oh, and what’s fun is it’ll preview just fine if you don’t have it … then refuse to post it, which is apparently something plenty of users and even owners of Discourse based forums commonly complain about on the software’s support boards. Yep. The problem here is largely control freak upstream devs, rather than Blizzard.
Fun thing with Discourse, even as a MODERATOR using the software you can often get your actions denied, because certain things work with respect to the original user’s permissions rather than the moderator’s (e.g., moderator tries to move a post and gets told no because it would exceed the OP’s posting limits … yes, this kind of hogwash actually happens).
Also the Discourse devs are actively hostile to many forms of permissions customization - e.g. Trust Levels are notoriously inflexible (you can modify the requirements, but a lot of stuff related to TL is hard coded), and Blizzard actually had to custom edit code to enable us to opt in view flagged content - yep, they actually HARD CODED the inability to see it a while back for anyone but TL4 and moderators.
They’re nearly as bad as Google when it comes to making unilateral decisions on behalf of communities that use the software, honestly.
Trouble is there’s not a lot of alternatives left these days for traditional forum software; most people seem to have moved to Big Social Media (see how many news/blog sites for instance outsource their comments to Disqus, Facebook, etc. instead of having in-house setups) and a lot of forum software goes un- or under-maintained (leaving you with constant security and bot problems, which is what Discourse’s devs were trying to solve with all this) …