teh Assembly people woudl be mixed, soem woudl be the local gentry and others the "second set", businessmen, perhaps well to do farmers, professionals etc. Darcy as we're told has OFTEN been haughty and given offence to people... but I think that Austen makes it clear that the people who have really taken offence at the MEryton assembly are the local gentry.. The "second set" would not really expect him to ask for introdcutions unless one of them had a singularly beautiful daughter, but the gentry would and we know that Darcy declined being introduced to anyone, even Elizabeth, a local gent's daughter, and danced only with the ladies of his own party... Ther's no evidence of Emma snubbing people who are her own rank or just a little below it.(as Darcy did) and while it would have been KIND of her to take notice of Robert Maritn, she certainly wasn't obliged to do so...and would not have been seen as particularly haughty in not asking to be introduced to him.....Its just a fact of life at the time that the Martins as farmers were not the equals of the gentry... and did not generally socialise iwht them...Emma is not at fault for thinking this, only for trying ot persaude Harriet not to marry Robert. and Harriet is not to blame. She's not very clever, she is fond of Robert but with Emma putting ideas in her head, she is naturally flattered and willing to be pleased by the idea that she might marry a gentleman..