The mourners have part in the innocents deaths.
Let me give you a clear explaination and first you need to understand the enemies mentality. This is a weak enemy I mean mentally hence it will look to eat any credits it can get.
Example Hamas themselves and PIJ have nothing to lose and harming them is very difficult as majority of them have accepted death long time ago hence you can´t do really much damage to such individual who is fighting to the last man and willing to embrace martyrdom there is absolute nothing you can do to that person.
Hence Israel found a window of attention with the mourners who everytime a single person dies mourners like the whole world has died and the Israelis said wait it minute this is the only way we can hurt them as they are immune to everything else and that is how they keep going in order to get into your headlines we have Jazaeera, Press Tv as the mourners.
Example the Russians used something similar in Syria they were fighting for 5 years the rebels and Russia would revert to taking Civilians because that was the only window of opportunity Russia was getting mourners from and attention.
Example Russia tried to do the same thing in Ukraine but guess what THE Ukrainians don´t give a fuk about innocent people die hence Russia just stopped it because they aren´t getting mourners and they don´t feel it is doing damage.
Another Example The Israelis had massive casualities from the 12 day war around 1000+ people died but Israel kept hiding casualities and just kept hiding casuality aggresively and only admitted to less then 20 deaths.. The Question is why are they doing this because they don´t wanna give the enemy a window of opportunity to say this is how we inflict pain on them and they target more civilians to put it short Israel could lose 100.000 in a single day but they will never admit it but maybe say we lost 30 people because they will never show you their underbelly.
It is like cat when she trusts you it shows you it´s underbelly but Israel will never do that becasue they don´t wanna give the enemy the opportunity of window the mourners on the pali side gave them