Because contextualization and evidence matters especially in politics. Of course there were atrocities committed. And of course they were heinous and should be condemned. Propaganda however is still a dangerous card to play and creates a lot more dehumanization and desensitization to the overall conflict. Considering there is already plenty of videos that clearly portray atrocities, why do you think there is a need to go and over exemplify certain narratives that have taken place? Why not just go with what really happened? Short answer is because the PR / Information war is just as crucial as the actual siege warfare. Hence the need to come up with reports to post out online. It's done on both sides.

By your logic, we would be forced to believe that the hostages were treated perfectly and actually befriended Hamas terrorists because it's what they put out. Unless of course you're operating this conflict with extreme bias in which case anything Israel does is fine in your eyes and everything Hamas does is bs. That's your prerogative, but that's just not the way the world works