What I was talking about was codec at least in USA you can not play music of certain formats without buying licensing or codec for that. Even the great Microsoft can't work with Blu-ray because of licensing. Now Ogg is of course open source format which is free for anyone to use in Video or Audio. But as far as other formats... Many could play audio and video formats in browsers like Firefox but they don't want to mess with lawyers and don't want to pay for codec on a free browser.
The comparisons aren't exactly the same with somethings like you mentioned Youtube technically the people posting music up there without authorization are breaking the law could be fined heavily. PlayStation you mentioned is "SONY" a corporation. Who owns the patient on many music formats causing this problem for everyone "Sony" AAC/mp4 Codec, "Sony" even owns artists songs a major record label is Sony (Britney,Prince and hundreds of others).
The other thing is also illegal in USA you can't pull sheet music of modern music it's also copyrighted unless it is public domain so you could pull the stuff like classics from 1700s or 1800 or even 1 century music but if you wanted latest Justin Beaver song might run into issues of course what players do on their own, Red and this game has no legal responsibility for.
Just one example of codec they patented: AAC was developed with the cooperation and contributions of companies including AT&T Bell Laboratories, Fraunhofer IIS, Dolby Laboratories, Sony Corporation and Nokia. It was officially declared an international standard by the Moving Picture Experts Group in April 1997. It is specified both as Part 7 of the MPEG-2 standard, and Subpart 4 in Part 3 of the MPEG-4 standard.
So of course if your PlayStation "aka Sony" you would have no fear of being sued for a codec, in fact Sony will be the one giving you the lawsuit. If you look google "sony lawsuit for music" there's just a mess you don't want to be part of.
But overall your statement is correct I don't think anyone will mess with you in most situations. I recommend using a standard open source music format like OGG rather than note-blocks, I think midi format probably is usable. I want the game better than minecraft in all things lol. But to clarify I am not saying don't do it but just be aware of the format used is free to use so Red51 doesn't have to pay royalties for codec.