@sparkiegeek - note that upstream is not handling this and your point is accurate for SNAP_USER_DATA: a snap is free to break itself and these are just bugs in the snap.
However, my point is different and I disagree with your assessment as it pertains to personal-files: ~/.config is where apps installed by traditional package managers and ‘make install’ will look at configuration. We set $HOME to $SNAP_USER_DATA and don’t expose ~/.config/snapname by default for precisely the reason that we don’t want the snap to break the application installed via other means and vice versa (consider a happy user of guvcview that tries the snap, which upgrades the ~/.config dir incompatibly: the user can’t go back to the deb). This is why there is the question of how the software deals with forward and backward compatibility when granting write access for personal-files/system-files, especially since the snap is not coming from upstream (as is this case).
There seems to be confusion on what personal-files and system-files are meant for so I updated the descriptions:
(I encourage all @reviewers to keep those in mind when voting).