There is no block equivalent, only mute, so if your client has a “Block” button, it does nothing to prevent someone from reading and responding to you, and chances are, they won’t even know you muted them unless they know how to check your public mute list. Also, clients don’t always handle muted users the same way, and you may end up seeing their posts again if you change clients.
That said, don’t be afraid to use it, because it improves your overall experience. I’m using it more, with so many bad takes on all The Current Things™ flying around lately.