the main motivation here “should” be that users are less willing to depend on packages pre-1.0
if packages instead are pressured to be pseudo-stable once they have users (no matter the version number) then users have no such incentive to care if the package they use is pre- or post- 1.0
good documentation is a crucial part of any good package, regardless of stability status. if we want to enforce quality standards in General then we should enforce documentation standards, yes. I just don’t think that “breaking” changes should be singled out because “breaking” changes are supposed to be a dime a dozen pre-1.0, per SemVer