I will clarify that this is no longer the case. When silences were introduced, we adjusted our chat specific penalties to be the ‘ever doubling’ silence. Unfortunately, we found that this did not serve as a sufficient deterent to inappropriate language.
We’ve reintroduced suspensions for chat penalties, so silences no longer double indefinitely. You’ll receive silences initially as a warning, but continued chat related infractions can lead to suspension and even account closure. This is more of the standard “Penalty Volcano” that folks may be aware of from the past and other Blizzard games.