it would just boil down to the question of scale
Now you get it.
, and with allow lists that should almost be a non-issue (not saying it won't happen, but significantly less frequent),
But you still do not see, that there is no such thing as private messages on a website. They have to have moderators to intervene. They are accountable, if they do not act upon reports. (Oh, and what you call allow list ist just another word for a friend request and a whole infrastructure behind it)
And while we are at it, do you propose private messages on youtube as well? Oh wait, they had such and abandoned it... ;-)
But are you telling me this is actually one of the reasons Itch won't implement the feature? If so, that would be a "reason" not to have any private messaging system, anywhere.
That was in response to your reasoning, that those messages would be "private" and hence would not need moderation and some simple features would hand wave all the issues. At least that is what I understood from you. You invoked something like that to the explanation that such messages would not be implemented "because they would be a moderation and privacy nightmare".
Just because itch is not willing or able to tackle those issues does not mean no one could. But as I said, this costs money. I see no advertisments on itch that would pay for such a service. And all those services that are "free", are services where you are the product.
Not very familiar with a lot of other services, but that takes nothing away from the potential viability of the proposed solutions.
Actually it takes away quite a lot, like most of it. In other words, while you know nothing about running a public website with users accounts and having not observed any supporting evidence for the viability of your solutions you could cite, you think you know better than the people actually running such a site. If they say there are problems that are nightmarish to solve, I tend to believe them more than you.
Bottom line, there are issues with such features. The details or wording of those issues are not really important. In the end it would just cost money to overcome those issues.
Your account is older than mine, did you never see comment sections, where people tried to scam developers? This even happened in public message board. Out in the open so to say. I shiver at the thought of the new hunting grounds the bad guys would get, if itch would implement a direct message system. Right now it has to occur in mostly public places, where not only the scammed could report, but anyone reading it could alert a moderator that something fishy is going on.
Steam has such bells and whistles, but they ask 100 bucks from wannabe developers up front and I believe they have harder sanitation for user accounts as well, And of course, they practially only have paid games or advertisement games, whereas most stuff on itch is free/pay what you want and advertisment is even frowned upon in games. I am not even advertised games on itch, unless I specifically browse for recommendations. Log into steam and you see game ads. What I am saying, they have the money. Itch does not. And implementing such features will not increase the money itch has to pay for the feature. In the long run such features might do good for a platform, but there probably would be a whole eco system needed around it. Itch does not even have public reviews or user tags.