It's not necessarily so. It works also for groups. Example: at a time when 'object orientation' was still kind of new (early 80s) lots of Lisp-using groups were

It's not necessarily so. It works also for groups. Example: at a time when 'object orientation' was still kind of new (early 80s) lots of Lisp-using groups were developing OO-extensions for Lisp: Flavors, LOOPs, CommonObjects, ObjectLisp, ... These language extensions were used in groups at TI, Xerox, HP, Symbolics and others. For example Symbolics wrote much of their operating system and their applications using Flavors (-> several groups of people used it as a standard language extension -> incl. their customers). With the Common Lisp standardization, a subgroup was given the task to decide on a standard object-oriented extension or to develop their own. After several years of work, a core group with a large group of supporters and implementors then defined a standard language extension to integrate object-object-oriented programming in Common Lisp - the Common Lisp Object System, which is now widely used in Lisp.