To put it brutally, the musicians in bands I grew up listening to have been dying since the 1960s. That many of them lived until the past year or so is simply the realization that some of them made it. In the early days they died of drug overdoses, extreme alcoholism, accidents, sometimes suicide or murder.
Some died later on from the same things.
Some died later from the lingering affects of one resulting from the other.
These days, cancer and simply old age are taking their toll. It's really sad to say but we can expect this to become more frequent in the next few years. We're lucky to have had some of them stuff performing as long as they have.