According to the video, one-button builds will likely be possible in Path of Exile 2 (POE 2) but it’s not a design goal of the developers.
The developers mentioned that they don’t want to actively encourage this playstyle, even though it might be achievable.
Here’s a conversation snippet from the video that talks about one-button builds:
Interviewer: I have been getting this a lot about poe2 will people still be able to play one button builds cuz that’s been happening a lot it seems like everything’s combining but people are pretty concerned about will would that still be a possibility
Rory: I can’t see a way that it would end up being more efficient than using your skills in a clever way but laziness is increasing…sure there will be ways to do that but I wouldn’t say it’s a goal of ours to preserve…
The interviewer asks if one-button builds will still be possible in POE 2, and Rory acknowledges that there likely will be ways to achieve this. However, he emphasizes that this is not a desired outcome and their goal is not to promote such gameplay.