Calling the situation as fragmented or duplicate is unfair for these existing groups/communities/magazines (whichever word you want to use), because they were here first and already well-established.
Putting all your eggs in one basket is a recipe for disaster. We already experienced that when Guppe went offline for almost a week, and almost permanently shutdown if the financial goal was not met. And that's just one example, for years we've witnessed instances disappearing or shutting down completely, just like that, communities were destroyed.
The lesson we should've learned by now is this: redundancy of communities/groups/magazines spread through out the fediverse through different instances is vital for the continuation of discussions. If one instance goes down, there are other existing communities/groups already in other instances. We can minimise the disruption that such a situation can cause. This is important for those users who rely on groups for content, instead of following every single user.
Instead of looking at it as fragmentation, which is very negative in this context, look at it as redundancy and continuation. There are a lot of ways for the free instance you are using, or hosting yourself, to suddenly disappear.