If that's the case, that's incredibly misleading. Especially because that's not undiscovered by human players, just by the OpenAI team, if that's what it is:
https://blog.openai.com/more-on-dota-2/"Sumail pointed out that the bot had learned to cast razes out of the enemy’s vision. This was due to a mechanic we hadn’t known about: abilities cast outside of the enemy’s vision prevent the enemy from gaining a wand charge."
That's not an undiscovered mechanic in the world of Dota - that's been known for a while and at least documented since 2015 https://dota2.gamepedia.com/index.php?title=Magic_Stick&oldi....
I wouldn't be surprised if it was known before then, I certainly remember this from a while back.
Again, if that's not what it was, then I take back what I said, but if it was, I do think that statement is misleading as written.