There's a few reasons why people want it to be private.
First, keeps randoms that aren't invited out.
Second, makes it generally easier to maintain the member list.
Third, some just want to get on the bandwagon.

The best way to think of advertising a private group is setting up interviews. This way, you can choose members that you would want in your group rather than have low quality members, as determined by your own qualifications.

We just want to make leechers jealous of our great groups. :P

I myself have two, for different groups of people.

I have a private giveaway group and I will never advertise it in the forums.

So they can find more people that they would want.

I spent 20 minutes thinking up this incredibly difficult concept.

If its a private group, why do people get contributor value for every giveaway, not just for the ones in the group?

(because the contributor value helps to motivate people to gift, but all the little groups make it more difficult to win smth, so that sucks)

I am going to make a private group that just has me, myself, and I. That way every time I give away a game in it, I win it. Woot.

All joking aside. I made this thread mostly out of response to the number of posts I found on here with private and group in the title. It sounded so contradictory and silly. I do believe private groups can be rewarding to those who contribute just for the sake if doing so. I just hate seeing people being all about the numbers and values instead of what it means to the community.

You're confusing Steam's terminology with everyday usage. For Steam, a 'private' group means membership is by invitation only, while a 'public' group is one anyone can join if they so choose. That's all.

What's up with insulting hookers and strippers? There's this really weird judgmental undercurrent in Steamgifts lately.

Psh, I have a public group that I never advertise and no one makes any giveaways for (as far as I know) except for two copies of The Ship I did ages ago. Yet somehow I'm still getting a pretty regular stream of new members.

well its basically like a public group except they can choose who they want in. How open people are about them is determined by the poster, but they're generally made to invite people they think would be a good fit. People's private "favorites" groups are different, if someone posts those, id agree thats pretty stupid because you should know your favorites.

I am glad to see some good discussion in here. I made the topic in the wee hours of the morning while suffering from insomnia.

Because I don't want to invite people (that I know) without their permission. I get a lot of Russian group invite spam so I know how it sucks to get unsolicited invites. Also there are so many people that I want to invite that I don't remember their names (only avatar) but sometimes it's futile to rely on avatars to remember people because they like to change avatars frequently (yes I'm looking at you glassfille).