If you can't find more diverse modern music than the top 100 offers today you're not trying that hard.
This is not about being able to find this or that niche musician that's great or even greater than any in the past, but about what the masses listen getting worse.
Music isn't just a solitary experience, but also a part of general culture.
As streamed music is getting cruder over time, the majority of the people are listening to increasingly shitty songs. That's chilling, regardless of whether someone can find 10000s of niche bands to listen themselves.
Your data might be objective, but it's still a narrow slice of a much broader ecosystem.