Not compiling everything, just a few pieces of software you want with different flags.

Always thought that the point of Gentoo is customization, not optimization. Hence “gen” in the name.

My laptop is not old, but this makes using Gentoo theoretically possible for me - installing stuff will be faster.

I see it as just another option. There are some packages that are annoying to compile (and don’t yield much performance gain from doing so) that can now just be pulled from the binary cache. The old way was to have specific -bin packages, but that is a bit arbitrary and presumably this is a bit more scalable.