The only real answer to that is to add a delay between each message. At the end of the day we need some kind of communication. Marking players and pinging the quick chat that you're attacking said target has proven in my experience to make a significant difference in focus targeting. Its obviously not a guaranteed thing, but matches tend to go much smoother when that feature is used, especially on bard when I tag the player I'm about to silence. I wait to see if my team responds and then I silence them and do my burst combo. Leads to a kill most of the time.

But I do agree the straight spamming of it can be pretty annoying, especially from salty teammates when we are losing.