I do not use Mastodon and if it was the only option, I would not be on the Fediverse at all. Thankfully it is not the only option.
As far as what I would say about the Fediverse's distributed nature. I would point out the benefits of not having one person, the owner of the centralized social media, make all the decisions. They might even force you to only have one type of Instance 
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There is a large range of benefits though the top is that no one person will ever control the Fediverse. It was designed to prevent that from being a reality. If a person wants to have someone else make all their decisions for them, then I guess centralized social media is for them. It is definitely not for me. I love the extended control over formatting and style we have. I love the way we can decide what gets propagated (by interacting with it) rather than having that central authority make the decision of what we should see propagated.