The opt-in and out isn't simple as you think, steam even had problems with it on their end. Many people would forget it existed or never tryed to opt-out. This is why it can never be a feature, it can be abused.
Viewing post in Collect emails on free download
devlogs are for reading, you dont give away anyone infomation and uploading melwere thing is impossable.
Publish projects are not that abused with itch.io scanning and players reporting it. mods remove it quicker than steam.
you can not control feeds, there is no rule on it like steam.
game jams are game james, people can report any jam that looks like a scammer might steal their info.
What you want with email can be abused for both gamedev and players, the infomation is not going to be accurate. ask anyone in steam when they ask for email, you'll see how easy it is to just add random fake emails into the list. steam even allows fake emails to be counted as accounts. nothing about the email marking is ever going to work.
can you describe me how the moderators and players aren't in the control of the feature I am talking about? Or do you really want to ignore everything I said regarding the fact that we don't have access to players' emails because that's on itch.io's server we can only use general categories to add them to our email using itch.io's build in emailing tool?
Your feature isn't made, there are hundress of ways to make it. And you keep adding new things that were not talked about. Also, the video talks about people entering your email list, not forcing it on them with "hey you want to download this, you need to give email". The guy said it has to be by the user giving it away to you not doing many sneaky things, that is not ok.