> it's up to you who you follow and what exactly you read on Twitter

The Twitter experience is a highly algorithmic feed where tweets from the people you follow are not guaranteed to be in chronological order, or even shown to you at all. The default experience also mixes it other tweets "you might be interested in", that is, things they want you to see.

There's also the fact people could freely see tweets and follow discussion threads, that's now locked behind an account requirement.