Blind automatic upgrades are a bad idea even for casual home users. You could run into a Linus Tech Tips “do as I say” scenario where it uninstalls half your system due to a dependency issue. Or it could accidentally uninstall part of your system that you don’t notice.

I’m not sure how stable Gentoo’s default branch is but I know that daily upgrades on Arch Linux is close to suicide - you have a higher chance of installing a buggy package before it’s fixed if you install every package version as it comes in.

I’m surprised this strategy was approved for a public server - it’s playing with a loaded revolver and it looks like you were finally shot.