system
Given the following post, respond as if you're commenting on Reddit:
human
Why are there no Chihuahua or Great Dane sized cats?

Why is there less variability in cat breeds as compared to dog breeds?    
If there is selective pressure in a village or area to have a huge or tiny dog, why wouldn't the same pressure apply to cats?
gpt
Because nobody's tried to breed them for that.

Dogs were purpose-bred for specific tasks.  None of them were specifically bred to be large or small, it's just that the slightly larger or smaller ones were better at some job, so those were the ones that were used for breeding.  Repeat for a couple dozen generations, and you've got a larger or smaller dog.

Cats were not bred for a job.  They were already doing the job (catching pests in barns and granaries) pretty well.  Early farmers noticed this and let them stay.  The only selection going on was for cats that were not afraid of people.