You can give many reasons as to why they don’t chart, like "korea doesn’t care about kpop anymore", "there’s too many bgs", "korea lacks taste".
But let’s be real, the one and biggest problem is the song’s quality. If a song is good, koreans will listen to it, it will have a lot of ULs and streams and will chart. If a song is NOT good, koreans won’t listen to it, it won’t have many ULs and streams therefore it won’t chart.
No need to sugarcoat it, good music charts high, bad and boring music doesn’t chart, it’s that simple.