Yes.
If no one on, say, mastodon.social is following you then none of your posts will show up in the global timeline there or in searches or in hashtags.
Also if you have few followers your posts will receive few boosts so hardly anyone will follow you.
So we end up with a handful of wildly popular accounts dominating the conversations which mostly happen on the big instances. Centralised power. Bad.
The threadiverse solves this. People don't follow other people, they join communities and it's their membership that determines where the federation traffic goes. So nearly every instance has all the conversation and everyone is on an equal footing.