It is site practice to delete unsupported answers
Admittely it's never really documented/discussed on it's own, but mostly in the discussions around fun topics like game recommendations and designer intent requests. Specifically, when the questions type really needs supported answers, aren't getting them, and we need to talk about how to moderate them.
"Why ..." doesn't necessarily mean "Why did the designers ..."
Possibly I've spent too much time adjudicating legal disputes but I find the answer to "What happened?" is far more useful in determining the "why" than "What did X say was the reason that something happened?" X is always an unreliable witness.
Tangentially - you can check for this type of edit (or any others)
This is the 10 most recent Unprotect edits using:
SELECT TOP 10 *
WHERE PostHistoryTypeId = 15
ORDER BY CreationDate DESC
The PostHistoryTypes are: