❓ Why can't a player spectate a match they disconnected from?

#Answer

This is deliberate and cannot be turned off.

A player who leaves a match, whether by disconnecting or by quitting out of it, is barred from returning to that same match as a spectator. Without the rule a player could drop out of a fight they were losing and immediately come back to watch their opponents, which is an obvious way to scout or to grief.

The restriction only covers the match they left. They can spectate any other match normally, and once that match ends the restriction is irrelevant.