If you don't want to envision your Free Company as something that you and close friends share, it is your own choice. It only takes 4 people to make a Free Company and they have yet to say any population caps on Free Company Alliances.

Linkshells being strictly chat channels has been stated for quite some time for ARR, and in all honesty it's all they ever were in FFXi or FFXIV 1.0 (only variance being better but still poor management options in XI and a header).