Rocky has community. The community is the users. Peers, who help each other. You (and I) are part of the community. You help others as much as you can. That is the “support by community”.
Red Hat releases a patch for RHEL. Rocky maintainers find source code for the patch and build it for Rocky. You paid nothing for Rocky, except the time it takes for the patch to be released for Rocky.
If some third-party offers packages for Rocky that replace what is in Rocky, then that (paid support) renders the system not-quite-Rocky. That can be fair trade for some cases.
The AlmaLinux chose to not be as similar to RHEL as Rocky is. Still very close. Nevertheless, they have more need to tell about things “not in RHEL” than Rocky.