> The number of times I was asked to lunch with "the guy in accounts or the women in the sales team"

The fact that you read a comment saying that people have lunch with each other and respond saying you've never been asked to have lunch with anyone is interesting.

I guess it varies by company and what the culture is, but it's surely totally normal to just have a friend in sales or something and hear about something going on.

I really doubt the person you're replying to orders people to have lunch.