It seems to me that such an option is not very difficult to implement

This is actually something that is very hard to implement. Since all jam submissions are just pages on itch.io, to have a truly anonymous submission that someone can’t just go and look up, you would also need to strip author information from everywhere else on the site. We will never do that, since it may be misleading to those accessing pages not through the jam, in addition to creating basic usability issues with other functionality throughout the site.

The best way for someone to have an anonymous submission is to create a new account for their submission and not include any other information.

Please do keep in mind, although we let creators manage multiple accounts for different projects/groups, using multiple accounts maliciously, eg. to circumvent account restrictions or create fraudulent activity (ratings, views, etc.), will result in suspension of all accounts.