Only link to Sign-ups on primary site admin of primary network

[johnjamesjacoby]

User sign-ups in WordPress are weird. Like users, sites, and networks, they are truly "global" to the installation.

It seems weirder, then, to link to sign-ups from a site-dashboard on a multisite installation. Since sign-ups are global, they should be a top-level menu-item in wp-admin/network, and I think showing pending users in a site's users list-table is potentially the wrong place.

Given the multitude of ways that BuddyPress can be activated in WordPress, and also given that the 2016 survey showed that many people exercise their option & right to do so, I think where sign-ups are exposed in the UI needs further scrutiny.