I was rather wondering the same thing. Sorry for what happened to that lovely lady, but I have opened many a wardrobe in my day, and not one ever fell on me.
Given the construction quality of mass-produced modern furniture, it's hardly surprising - the plastic screw-on joints frequently pull apart, since only craft carpenters bother to make proper timber joints these days. It's more likely the wardrobe was actually light rather than heavy - she was just unlucky to be caught by the edge of a board which somehow became trapped