Another reason to thank open sourcery
Is the heroic efforts sometimes invested into compatibility of various sorts, from MAME for venerable video game systems to providing alternative viewers for legacy formats - I almost cried with joy when I realised I could play an .rm file with VLC rather than polluting my system with that RealPlayer shite.
Of course it does depend upon people finding the topic of legacy formats sufficiently interesting to invest that heroism but this seems to happen pleasantly often - perhaps because it's basically just puzzle-solving.