It doesn’t “have to.”
It can, if you want it to, or it cannot if you don’t.
There is absolutely nothing to stop you attempting to engage at a less formal level if you want.
Conversely, there is absolutely nothing to stop the other party(s) from disinclination to engage if they are so minded.
The party that feels wronged must decide what level of redress they reasonably desire and then proceed appropriately.