That was not the point. Lisp applications were already a team sport back then. That all or even most Lisp software is written by single person teams is just wrong.
Modern agile development is far more complex than even that: you need entire loosely-coupled teams of developers to be able to seamlessly cooperate with one another, so there are multiple scales of cooperation. Tightening the semantics of interface boundaries is a necessary support for that kind of development and is what's largely meant today by programming "in the large". Highly dynamic "scripting" languages get in the way of this, and that's essentially what Lisp is too.
Lisp isn't essentially a scripting language. Common Lisp was designed as an application language, in rare case it's also a systems language. On a Lisp Machine, for example the whole networking stack was written in it.