1. Even software with no "accidental" complexity is necessarily complex (in fact, that's why it's useful).
2. If the manifesto's point is that we should stop over-complicating things, then wouldn't it better to first examine whether, and if so why, things are overcomplicated now, given that the previous generation also went on a crusade to abolish (over)complication? If the point is to declare "don't overcomplicate!" then, if you believe things are overcomplicated now, why is that declaration useful if it's clearly not effective?
In the early days people usually lived close to water bodies (rivers, lakes, etc.) because the closer you lived to the water the better your society thrived (water being essential for live, agriculture, transportation, etc). But there is a limit where if you go too far (i.e. into the water) the benefits evaporate possibly reversing the benefits (building houses into the water adds complexity, flooding, etc).
So there is probably a (global?) optimum that is neither too complex nor too simplistic
Except for that special guru who writes The Framework for the company, because why not a Forth-based DSL for everyone to work in? Overblown, I know, but there are kitchen sink types, or those who just don't know that there's an easier way, and other reasons to wind up with too many tools or layers or libraries.
(I've been guilty of not knowing easier ways, so...)