Not because of any bosses, but because one of my ps4s died with Sekiro still inside.
Sekiro is awesome! Kind of wasn't sure about it at first playthrough, having been a Souls veteran and Bloodborne is possibly my favourite game of recent years. But (when I find time that is) I have persevered and really come to appreciate Sekiro. FromSoftware are true masters of a craft and honesty this game is great re-imagination of Tenchu (and those games were awesome also).
Our PS4 disc drive stopped accepting discs a while back and we couldn't figure out why for some time. That is, until I opened it all up an discovered my youngest child had inserted a playing card, 20cent coin (Aussie) and part of a chicken bone! It works quite well now actually.