If you mute someone, they can still see your tweets though, and tag you and mention you. When you block someone, they know loud and clear you blocked them. With muting they have no clue. Blocking get rid of them completely, which is why it’s such an important feature for some people.
It’s not immature for example if someone is a legitimate predator or is harassing/trolling you and you want them to be blocked so they can’t interact or see your content at all or mention you. That’s logical. This opens the flood gate for people like past harassers and abusers and bullies and trolls to stalk their victims or who they troll. You won’t see them, but they can absolutely see you.
If someone sent me death threats or told me to “kys” or were an adult predator trying to interact with me, I wouldn’t want them to see my content or posts or be able to mention me again. I wouldn’t just mute them, I’d want them to not be able to even see my content forever, and be gone from my life.