To conclude, my point was: if people don't want to use NSFW tags for NSFW content, the federated timeline is going to be considered harmful for most "maintream" users that don't want to spend their time on the platform filtering out content, and Mastodon won't become the new alternative to centralized social media.
Moreover, "safe" communities dedicated to using mastodon will isolate themselves from other instances and yes, federation might lose appeal at some point.