The impression they want to give is that Israel is even attacking the dead.
Back in 2014, the IDF released figures of how often Gaza terrorists shot rockets from civilian areas:
Approximately 260 rockets were fired from schools.Approximately 160 rockets were fired from religious sites, including mosques.Approximately 127 rockets were fired from cemeteries.Approximately 50 rockets were fired from hospitals.
Cemeteries are ideal rocket launching sites, and they are used all the time.