But if someone is doing no harm, but just posting things you don't want to see, just unfollow them. And if they keep showing up in your timeline, block them. You'll both be happier.
One of the great things about the Fediverse is that your feed is your choice. If a platform forces ads or commercial content into your feed that you don't like, you can change platforms. And if you can't find a server that has the same values as you do, you can set up your own.
If you have a fediverse account, you can quote this note from your own instance. Search https://cosocial.ca/users/evan/statuses/114485853307600571 on your instance and quote it. (Note that quoting is not supported in Mastodon.)