I agree about this. I like Google Music and unlike Apple Music it didn't and doesn't want to delete all my music then shrug and say it's my fault for not buying from Apple, but... I can't even use youtube while my 3 year old daughter tries to listen to her bath music.
It happened to me with several hundred PDFs of sheet music from IMSLP that I was storing on iBooks. I couldn't work out where they had gone or why they were wiped. I switched to GoodReader and painstakingly had to rebuild the entire collection.
It's pretty ridiculous.