Keep in mind the bulk of the comments in this thread are over a year old. I haven't read an article about people losing their music in a long time. Apple Music now has 27 million subscribers, so it is adding a million or more a month (on average). I would still recommend that anyone starting the process makes a backup of their music files and their iTunes library files, though.I read threads like this and know I'm making the right choice by not using streaming music services. I've just tried Spotify and it's crap. Seems like I actually have to have a paid account to use it fully. The "free" option sucks.
Also, if you trusted MacRumors comments for everything, I doubt you would ever own anything from Apple, most of the threads on the main page have a high percentage of Apple-hating comments.
Yes, they want the free option to suck bad enough that you eventually pay for the service, but not so bad that you stop using it all together.