I've heard exactly the same response before and I shared your reaction.
The other thing that makes "dogfood" make sense is that sometimes you aren't the direct target audience of the product. So: would you feed this to your own dog?
The average person generally seems less than neutral to see me.
Many people aren’t just openly hostile, they make a point to immediately let you know they aren’t here to help, they’re here to make everyone’s life less pleasant.
With people, there are many scenarios where if you’re out of line, disagree, that’s it. You’re done. They’ll never ever consider you worth any reasonable sort of treatment.
The other thing that makes "dogfood" make sense is that sometimes you aren't the direct target audience of the product. So: would you feed this to your own dog?