I'm not sure why people do it... You're MUCH hotter than that Ty!!! I'll give you a ten ;D Personality included ;)
Why do people rate others on a scale of 1-10? I got told today I was a 5 >.< Upsetting... It's stupid, what's the importance?
Well think of 5 as 50 out of 100. Meaning 50% of the entire human population looks worse than you.
Society?
There's no importance. People can be stupid and mean.
Like you said, it's stupid, and so it shouldn't have upset you. Don't worry about it. People just say that to make themselves feel better about how they look.
It doesn't mean anything, little buddy! You're definitely a great person, numbers don't determine that. (but for the record, I'd give you a 10 ;D)