It would be nice if you could actually list the achievements you're referring to, but since you like being vague, I'll list all of them instead:
Hush Hush Achievements: Any hush hush that relates to score could be adapted to fit pp score. If not, then you can just achieve it by playing for score instead of pp. I have a few of those, and I don't see how any of the ones I've achieved couldn't have been achieved with pp score. Of the ones I do not have, only one of those seems to vaguely hint at being related to score - and the way I interpret it, pp-based scoring wouldn't get in the way of it at all.
Dedication Achievements: These aren't relevant to score at all.
Combo Achievements: ^
Beatmap Pack Achievements: ^
I'm sorry, but I don't think your argument is based upon anything you've even looked into. Also, I think that even if it was the case that pp scoring would get in the way of a single achievement, I would be surprised if you could find 10 people who seriously think that that is, on it's own, a valid enough reason to not implement pp scoring. That idea is absurd and you know it.
Hush Hush Achievements: Any hush hush that relates to score could be adapted to fit pp score. If not, then you can just achieve it by playing for score instead of pp. I have a few of those, and I don't see how any of the ones I've achieved couldn't have been achieved with pp score. Of the ones I do not have, only one of those seems to vaguely hint at being related to score - and the way I interpret it, pp-based scoring wouldn't get in the way of it at all.
Dedication Achievements: These aren't relevant to score at all.
Combo Achievements: ^
Beatmap Pack Achievements: ^
I'm sorry, but I don't think your argument is based upon anything you've even looked into. Also, I think that even if it was the case that pp scoring would get in the way of a single achievement, I would be surprised if you could find 10 people who seriously think that that is, on it's own, a valid enough reason to not implement pp scoring. That idea is absurd and you know it.