Deryck Chan, 30/08/2018 16:30:
without any prior notice on their user talk page nor any known process on how to regain that right.
This is more of a problem on wikis without bureaucrats, or with limited 'crat bandwidth. I agree that such wikis may deserve additional help, including direct talk page messages and a backup avenue for flagging by stewards.
I would be surprised if the English Wikipedia needed to be included in such a class of needy wikis. But yes, restructuring user rights often has unintended consequences, including an increase in instruction creep and a decrease in overall efficiency of the community. (We've had multiple examples in the past... from the English Wikipedia itself.)
Federico