Here's why:
* The concept of "strangers" is inherently about separation and lack of connection. Collective nouns usually imply a sense of unity or shared purpose, which doesn't fit with the definition of strangers.
* There's no common need to refer to a group of strangers as a single unit. We usually use more descriptive terms like "people on the bus" or "crowd at the party."
Instead of a single word, you could use descriptive phrases like:
* A gathering of strangers
* A group of unfamiliar faces
* A collection of strangers
* A random assortment of individuals
Ultimately, the best way to describe a group of strangers depends on the context and the specific nuance you want to convey.