The functionality in portage was there since forever the standard packages (think of it like a standard ubuntu install) were there for forever. They only branched out and offer more binary packages. Which is absolutely great but not a new feature... The headline is still misleading.
> we’re now also offering binary packages for download and direct installation! For most architectures, this is limited to the core system and weekly updates - not so for amd64 and arm64 however. There we’ve got a stunning >20 GByte of packages on our mirrors, from LibreOffice to KDE Plasma and from Gnome to Docker. Gentoo stable, updated daily. Enjoy! And read on for more details!
They've had a binary version of the full fat linux kernel available for a few years now. Other packages like firefox-bin have been available since before I started using gentoo in 2017.
Edit: Actually looking into this more the headline is accurate. This is the first time they've provided official binaries aside from stage3s when doing the initial installation.