You have three things going on in your post, some of which I agree with and some of which I don’t, but I think your views would be more clear even to yourself if you pulled them apart.

First, people in general tend to like the music they grew up with and then discovered on their own up to a certain age, and then they get pretty set in their preferences. Which is why older people generally say all current music is “bad”—it’s just simply not what they were trained to really like.

On the flip side, people who say old music is better tend to be ignoring survivorship bias. People always made shitty music, but shitty music gets forgotten. Heck, in the days before computers made recording and distributing music so easy, most shitty music was never even recorded. So, yeah, comparing all the music produced over 65 years from 1950 to 2015 is going to turn up more “good” old music because the entire pool is larger.

Beyond that, what you’re saying seems to really come down to personal preference. You don’t like Oasis because their music sounds nazzely to you. You also don’t like the Beatles, who Oasis drew from. It sounds like you just don’t like that style of music.

That’s totally fine, but if you’re really interested in music, it’s worth at least digging into why the Beatles are so popular. Even if you don’t like it personally, you should at least be able to appreciate the changes from their first albums to their last albums and understand that they helped drag popular music into the modern age. I don’t really like The Beach Boys, for example, but I do understand why Brian Wilson was a great musician, the influence he had, and why so many people like him.

As for Oasis, well, people are always going to like hometown acts that make it big. Personally, I think their music is fine and I grew up with it so I like it in that original nostalgic sense, but I’m not going to argue they’re especially groundbreaking or anything.