[astrobe_]

> The flip side is everything is being degraded by random mutation

"degraded"? Aren't random mutations precisely one of the core mechanism of adaptation?

[MarkusQ]

But most of them are still deleterious.

Remember, all improvements are changes, but most changes aren't improvements. The trick that makes evolution works is this: out of lots of random changes, most of which are harmful, the harmful ones tend to be weeded out and the useful ones tend to spread.