The Linux, GNU/Linux, and BSD ecosystem in general. Since most applications are portable between distributions, an improvement made by one vendor will eventually propagate through everything. A new feature in KDE Plasma will appear both in EndeavourOS and Kubuntu. A security fix in OpenSSH (which is maintained by OpenBSD) will appear in literally all distributions and even Windows.
(edit) This obviously doesn't include technically Linux/BSD systems like MacOS and Android. Their existence is sacrilege, and while they are on the council, we do not grant them the rank of Linux or BSD distribution.