I'm definitely an introvert (find large groups of people quite intimidating - enjoy plenty of time alone in the zone etc - found it difficult when dd was in at a very very clingy stage - much prefer spending time with small groups of people or one on one, rather than large crowds etc etc) but I have total sympathy with Aquitania's position.
But only when people use "being introvert" as an excuse to be rude. In fact it is a bit of a bugbear of mine. Can't bear it when people stand back and leave it to "everyone else" to oil the social wheels. (Although I know this doesn't apply to all introverts of course!)
We don't any more but we used to entertain a lot, and you really notice it in those situations when you are dashing around really busy and introducing people to each other but at times you are also desperately hoping that guests will oil the wheels a bit themselves.
I've had people come to dinner and chomp through three courses and not speak a single word to the person on their left or their right, which tbh, does comes across as a bit rude and and a bit lazy. (I was brought up with the instruction that if you were invited anywhere you had to "earn your dinner".)
The thing is though, no one finds it particularly easy to make casual conversation with people they don't know!
On one occasion, their partner excused their behaviour by saying "don't mind him, he's an introvert" - he was a 47 years old engineer who managed a team of 20 people at work every day fhs!!! And I'm certain we would have been really interested in what he had to say too!
I think the irritating thing about it is (as my late mother used to say) if you are "self conscious" then you are thinking more about yourself than about others. And sorry if this sounds incredibly old-fashioned but if people forgot about themselves for a bit and had an awareness that others might be nervous as well, tried to listen, and put others at ease, just made a bit of effort to grease the social wheels etc, then everyone would find it easier to get along - introverts and extroverts alike.