I share your opinions that a reason should be given in all but certain cases for a ban being imposed.
The other case you are referring to was of an escort who received a temporary ban for bumping up posts. Unlike other members, escorts make their living as a result of their advertising and participation on sites such as this, so we try to avoid doing anything which may unnecessarily damage their reputations and affect their earnings. The reputation which attaches to an escort's user/escort name is much more significant for her/him than it would be for the rest of us.