I don't get a lot of time away from my kids, I take them pretty much everywhere and think its be strange if we were invited to a friends house for dinner without the kids (out friends/family don't really do dinner parties).
However, to a wedding or engagement party, 30th, 40th etc, unless there is entertainment there for kids, I think it's unfair on everyone involved to take kids. It's not particularly fun for them, they get tired, they get bored and it's not really a good environment for them with adults drinking. at the same time, having tired bored kids around is stressful for adults so it's not fair on them either. I much prefer to attend these things without my kids. Babies are a different case though, as they usually sleep.
OP, I feel for you as we rarely have babysitters and I think it was really rude of people to comment on you having your child there, and I think the host is being a big precious giving you the silent treatment. I've had to take my kids to things they have no business being at due to no babysitters and it's really stressful.