Point of right is to stop newbie third parties from blocking themselves. Wikimedia has all sorts of help to deal with that situation, so we should not give anyone unblockself. Or at least limit it to say stewards/crats so they can deal with the case of a compromised account that blocks everyone, but we still stop average admins from unblocking themselves.
This is now done; per T150826#4809171 self-unblocks have not been used much in the past. Blocked admins are allowed to counter-block the person who blocked them (but not anyone else) to remove first-mover advantage of an attacker on small wikis. There is an [[https://gerrit.wikimedia.org/r/c/mediawiki/core/+/478581|open patch]] for rate-limiting the blocking of admins, to prevent an attacker from mass-blocking everyone else on large wikis.