Perhaps the ones from the late 1990s were (depends on what you think qualifies as "esoteric", since Medusa, for example, was serving high volume websites in the late 1990s), but I wasn't claiming they weren't; I was only pointing out that they did in fact support asynchronous request handling as a first class feature, even before Nginx did.

Nginx, OTOH, was popular before NodeJS even existed, let alone before NodeJS became mainstream.