> Because our training system Rapid is very general, we were able to teach OpenAI Five many complex skills since June simply by integrating new features and randomizations. Many people pointed out that wards and Roshan were particularly important to include — and now we’ve done so. We’ve also increased the hero pool to 18 heroes. Many commenters thought these improvements would take another year.

The linked commenters thought that getting to "real dota" (more than 100 heroes, captains mode instead of random, ...) would take another year. So I don't think it's fair to make that statement.

Edit: Don't get me wrong, I think the improvements are very nice, but pointing to people saying "these people thought we would need a year, we did it in under a month!" is not what you should do if you didn't actually do what the linked people stated.