I think no. 10 is responsible for the decline in the ‘quality’ of music in recent years. The fact is, since the beginning of time music has been inspired by existing music and its nearly impossible to avoid this issue. Otherwise you’d basically have to re-invent theory for every new song. But this helps supply one of the single most important aspects of a good song, familiarity and predictability (I say single aspect because these are two sides of the same coin).
Ever sit down with your instrument of choice, and start playing a few chords and think, “oh my god, I’m in the process of writing a huge hit!”, only to realize after adding the next transition, that it’s a song someone has already written? Or maybe even just that it sounds like another song. Even Bach experienced this. Then for a hundred years or more, everyone wrote songs inspired by advancements Bach made to classical music theory (in modern day terms we’d say, “ripped off his songs”).
Well, there is the root of the problem. Even when it’s not the same but maybe sounds similar, everyone then thinks about two things. The first being, “is this so similar I’m gonna get sued?”, and, “ will everyone call it a rip off?”. So many songs never get written because they ‘are too similar’ to another song and so many of the songs written now sound like nothing you’ve ever heard before. Innovation is key to a good song, but so is familarity, striking a balance is where the magic happens. If we have to compose with a complete disjoint from musical history, we’ve already lost the battle of finding that balance.
Always remember, imitation is the best form of flattery. And anyway, getting sued by a major artist is possibly what will put you on the map.