I am not aware of any software which prevents this. See my note on Mastodon’s related privacy settings in the PR:
The other privacy controls on this page should be read through, but we would stress that they are not technical controls, they are merely requests that you make to others. For example, if you choose to hide your profile from search engines on this page, nothing is actually stopping a search engine from reading your profile. You are merely requesting search engine indexes not publish your content to their users.
You will likely still wish to make these requests, because they can practically reduce your digital footprint. However, they should not be relied upon. The only effective way to hide your posts from search engines and others is to post with non-public (followers only) visibility settings and limit who can follow your account.
For this reason I am not very interested in requiring noindex requests as part of the criteria.
Separately from the option to have a private profile?
So we should require the option to have a fully public profile, except with hidden followers/following?
Mastodon allows this so it is not a problem, but I just want to be clear.
How would we handle social networks without followers/followings or even profiles at all?
I agree with @phnx that I would just not want to encourage this behavior actually. Interested in others’ thoughts.
These criteria are only applicable to instance hosts. We are not recommending any particular instances here, only federated software.