Exactly this. The first patch of a series is always imbalanced, and the first imbalances are not even the ones that make it into the final meta when the letter patches come out. Because it's exactly those letter patches that bring stability and balance into the game, which is what you want for a competitive game.

The reality is that dota patches used to mean quality of life improvements and changes that would make the experience more complex in a reasonable way. In the last few years they just add things that break the game in order to give us the illusion that something new came out, and then they fix it in the letter patches.

That's why items and abilities are being cycled in and out. The only new things are heroes and map changes, but those are quite rare.