The main point they're making in this self-reflection is how the Battle Pass has swallowed up so much of their time, and so much that could have been updates to the game was put into the Battle Pass instead in some form. This means they've had less time for other features for everyone and that "Most Dota players never buy a Battle Pass and never get any rewards from it" - which is really interesting to see them be so honest about it.
So what they ended up doing was taking away some developer resources from the Battle Pass, towards more main updates to the game which is what gave us the recent New Frontiers and patch 7.33 which they say wouldn't have happened if they were still going so hard on the Battle Pass.
Valve said they're going to now continue on this path, building a "wide variety of features and content for the game, delivered in different ways" but they will still ship various cosmetics over the year but they're aiming for bigger stuff for all Dota players to get.
Sounds like a sane idea overall. As they said "By freeing Dota's update and content cycle from the timing and structural constraints of the Battle Pass, we can go back to making content in the way we know best: by coming up with fun ideas of all scales and shapes, and exploring them with you".
I actually played a couple of games with a friend on the new map recently, and it was surprisingly a really great time. The map definitely feels a whole lot better now and the game works really great on Linux too.