First off, I like your post as a pretty good baseline. People aways ask "Why Lemmy?", because just saying it's a reddit alternative doesn't do it justice. You're trying to be careful with the word federated, which is smart, but it's its best selling point, especially for those fed up with reddit enough to consider an alternative.
I'll try my best an example paragraph:
Tap for spoiler
#Why Lemmy?
The web was designed from the ground up to be decentralized and open to all. These values are what made the internet and are being spat on by companies trying to seize control over the content and its users.
Lemmy is the internets response to an ever increasing centralisation of social media. Where every regular social media is owned by a single entity, Lemmy has no owner and consists of hundreds of intertwined instances.
This concept also connects Lemmy with many other forms of social media which are collectively reffered to as the Fediverse.
Giving instance suggestions is great and explaining the top few is a good move as well. Maybe group them by region or interest based? I like to stay away from my own biases when recommending instances and some people want to be federated with everyone.
Also, explaining instances without explaining federation makes it look like Lemmy is a divided mess, while in reality its a true melting pot.