The key on what you're talking about is how we define emphasis - traditional button emphasis might involve underlines or bold font… but, I'd argue that's quite a bit different than de-emphasizing things - purposefully making a button less visible is only something to pursue when that choice is dangerous or requires careful consideration (and we frequently do that with speed bumps like confirm() prompts on actions that delete data).

I disagree that this is only occasionally a dark ui pattern since it is purposefully leveraging our perception to make some choices harder to see and, if you have a choice to put in front of a user, make the options obvious and clear. I also strongly dislike this particular pattern because it is used so frequently to abuse our psychology and I don't like to see it normalized.

At the core there is a difference between trying to make one option more visible and trying to hide another one.