"New users are limited to 3 replies per topic"

Not likely because:

Although it doesn’t specify “in one Topic”, 3 replies is certainly not “…more than 10 relies”.

And, at this point, this is all that is really relevant.

Keep in mind that only Trust Level 3 can degrade. Once you reach Trust Level 2, you’ll always be Trust Level 2. My guess is, the only exception might be if you got banned, temporarily or permanently.

But, it is documented. It’s just that you experienced what might be considered an “unusual” issue. Probably due to this being a newly implemented system for the D3 Forums. As you already stated, it’s working now.

I’m sure Blizzard still has some glitches to work out.

As @Maskraider pointed out, this is what Trust Level 2 can do:

This is what Trust Level 3 can do:

And everybody can do this:

https://youtu.be/mk_hHOHbqZo

https://i.imgur.com/6PIA4Ul.jpg