This is true, but there are limits. It's a little bit like DEFLAT. Sure, very advanced compressors like Zopfi exist which can get better compression ratios.

This is true, but there are limits. It's a little bit like DEFLAT. Sure, very advanced compressors like Zopfi exist which can get better compression ratios. But then, there's also just Zstd which will get a better compression ratio and compression speed trivially.