Even if it's common, I still don't think it's good.
Some games seem to be made playable way earlier then in the case of Rome 2. Look at Baldurs Gate 3 and soon for Path of Exile 2 - all the content is not there yet but the main "game loop" and features are there, this seems like a great way to get feedback, and have time to adjust if necessary. In the case of Rome 2 I guess the management imposed deadlines that did not allow this to begin with. The author does speak of a demo for E3 but it seems like a small piece that was artificially setup to look good.
This might be a partial explanation why indie studios can be in meaningfully competition with the AAA-developers. They often integrate early and use beta, even alpha, early access. As a layman I find that approach more understandable. In my work, I always favore incremental changes to large process overhauls. We do have to understand that 10 years ago early access was a lot less common.
In the specific case of Celeste, the game was playable before development, because it was preceded by the PICO-8 version.
Valve did this a couple times by just buying out teams who made mods or interesting games - Narbacular Drop becoming Portal, that goo thing becoming the goo thing in Portal 2, Counterstrike becoming Counterstrike, then a CS mod becoming Left 4 Dead.
"Every big program that works evolved from a small program that worked" is even true for games
Some games seem to be made playable way earlier then in the case of Rome 2. Look at Baldurs Gate 3 and soon for Path of Exile 2 - all the content is not there yet but the main "game loop" and features are there, this seems like a great way to get feedback, and have time to adjust if necessary. In the case of Rome 2 I guess the management imposed deadlines that did not allow this to begin with. The author does speak of a demo for E3 but it seems like a small piece that was artificially setup to look good.