The Dark Forest problem posits that in the time required to send a message to a distant civilisation, the sender could just as easily send something that would destroy the distant civilisation. Further, that it is not possible to know without communication whether a distant civilisation would have peaceful or belligerant intent. Therefore, any civilisation that knows the existence of another should pre-emptively destroy the other rather than risk waiting to find out if it is peaceful
If FTL communication is possible, it could be possible to establish the other civilisations intent before they could send anything destructive.
As for the Sophon's it might be that they require a compatible recipient to work and so first require matter to be sent to the distant location. It's a long time since I read the Three Body books, but I seem to remember them being based on quantum-entangled particles, which would fit with this.
You need to physically send a Sophon for it to enable FTL, so the first message is not faster than light.
Near the end I think future civilizations communicate via dimensional membranes or some magic-technology like that, but it doesn't reveals your position either.
If FTL communication is possible, it could be possible to establish the other civilisations intent before they could send anything destructive.
As for the Sophon's it might be that they require a compatible recipient to work and so first require matter to be sent to the distant location. It's a long time since I read the Three Body books, but I seem to remember them being based on quantum-entangled particles, which would fit with this.