This version of "professionalism" has the stereotypical West Coast problem: the message it claims to be sending gets not only lost in translation, but distorted into something more superficially inoffensive, but underneath that, more opaque and manipulative. It encourages indirection and avoidance rather than respectful candor.

Let's start with the first example. The polite way to say "you are overcomplicating this" is "I think this could be simpler". Not "let's concentrate on initial scope", which isn't remotely the same thing in general. The latter is less generally applicable (how do we know there was an initial scope?), less specific (why stick to initial scope?), and more prescriptive ("let's do this" instead of "I listened to your idea and this is what I think of it").

Now, being less specific and more prescriptive may be some people's idea of effective self-interested corporate behavior, since it works to minimize your vulnerabilities and maximize the obligations of others. But I think communication is more meaningful, effective, and respectful if you explain how you evaluate others' ideas (which implies you at least gave them the respect of listening) before just telling them what to do.

They're not all bad though! I definitely think "that's a horrible idea" is productively replaced with some version of "I have these concerns" or "I think there may be better alternatives". It's generally good to avoid terms that communicate nothing but negative affect and instead communicate whatever ideas that prompted the negative affect.

EDIT: another comment mentions Power-Distance Index, which is part of a broader cultural dimensions theory. https://en.m.wikipedia.org/wiki/Hofstede%27s_cultural_dimens...

Apparently I have a very strong preference for low PDI culture, as do most of you. But it's good to be aware that that's not universal and our style may require adaptation for success with diverse audiences.