Well, certainly invites to things are a lot slacker than they were when I had one or two DCs, but I completely understand why!
Mine are rowdy yet friendly bunch, and take up a fair bit of space and feeding 
, if they happen to be invited to be somewhere when it's tea/lunch time.
We have many friends with one or two DCs, and tbh, if we turn up, I imagine those children feel outnumbered in their own home. But also, we're a lot of fun, I think.
I remember back in the day of having an only, my friend had 4 DCs under ...(can't remember, but just about a small as gap as you could possibly have). When her massive people carrier used to pull up on the driveway I felt a mixture of joy and dread of the imminent whirlwind (in retrospect, they made mine look like sleeping lions!) It was the knowledge of the mess that I'd have to clean up afterwards that used to get me!
I think if your DCs are pleasant (mine are) and have fairly decent manners (mine do) and aren't too loud (mmmmm....mine are very noisy,) people are generally OK.
I know several children with one sibling, who cause havoc when they come to my house...tipping everything out of toy boxes, never putting anything away, actually opening cupboards in the living room/kitchen (how rude!) and generally being very needy!
Having said that, I've witnessed two of mine being very needy at certain friends' houses 
.
For me it's not the number of children who come to my house, it's the behaviour. Even if there's only one child, if they think they can run riot and jump all over the furniture, and trash my house, it pisses me off. Times that by 3 or 4, and I'd be three or four more times pissed off, iyswim.
Generally, I have noticed that I am a lot stricter with mine than most of my friends are with their own DCs.