The thing this, and so many responses to it, miss is that #Mastodon is effectively only one of many different applications posting to the same #Fediverse.
A person doesn't have to write longer things somewhere else and boost them through Mastodon. Instead the person could simply write the longer things, and that is that. The content will show up on Fediverse whether it is written through Mastodon or write.as or whatever else.
The real way to look at it is that Mastodon limits what a person can write. Other programs don't have those limitations, which requires threading to make up for the artificial restrictions.
So you don't have to jump through Mastodon hoops to get around those limitations, you don't have to use Mastodon at all. Use the interface that works best for what content you want to share.