It always rubbed me the wrong way though, like the welcomer is trying to establish a hierarchy or draw attention away from the contents of my message itself.
Are welcomes a positive for some people? Or is this like starting Slack conversations with "Hey, how's it going?"
I believe fingering is what Americans would call getting to third base.
After a while it becomes an almost ritual hazing. Kind of like HR making you write a paragraph about yourself for an introduction email to a company. In spirit, it should help people find some common ground with you to spark a conversation. In reality no one actually cares, it's awkward for the person writing the introduction, and helps nothing except waste time.
On forums in particular I always hated these introductions because I don't really want people to know much about me on the internet anyway. So it became a tremendous effort to manufacture enough of a story it was consistent with my life (so I didn't forget), but different enough that I couldn't be identified.
Newbie fingering though...that's hilarious. I haven't heard a FINGER pun in a very long time.
They can be positive for me -- if they provide helpful information, explain -- briefly and courteously -- the expected etiquette of the group and set the tone.
That's the key: the tone. Is this group aiming for broad appeal and trying to be welcoming or is it a clique? Forget, for a second, how the users of the forum/group behave -- are the moderators, the sysadmin messaging and the like conveying the tone that is desired for the group? If a "welcoming newbies" is desired, then a welcoming tone should be used throughout messaging.
Unfortunately, being "welcoming" doesn't usually push away the less friendly/welcoming users. Being unwelcoming will certainly attract them and almost every forum site falls victim to it. It usually presents itself the first time you attempt to post something with a full page list of "WE KILL USERS WHO DO ANY OF THE FOLLOWING:", many items in red, often with words that "outsiders" don't recognize so they can't be certain they're violating them. Most posts, then, are from insiders with many "pissing matches" (we get bored, I guess?). Outsiders get trampled on and people complain that "we need better forum software that solves trolls/jerks" :)
I find myself agreeing with you in the respect that "welcome messages" are at least pointless. Fix everything else that isn't user generated, replace moderators with people who have empathy for new users, if "noise" becomes an issue (as it would on larger sites), machine learning coupled with requiring moderation for "first posts"[0] goes a long way. Generally speaking, though, you can't fix dicks. Most of the dicks on the niche forum sites are also the most knowledgeable users and the reason the forum site is so popular ... smaller forums, they're the ones running things. :)
[0] I'm thinking of the bigger problems QA sites get into where new users post the same question, causing hundreds of identical answers because new users often don't figure out how to craft the perfect search query (depending on the kludgy-ness of the forum software) before they figure out the reply/post button and they're usually making that first post because they have a headache already.
I don't think that's how it's usually intended, and I don't think that's how most people interpret it. I'm sure there are examples where it is, but that's not normally why people do it.
I have moderated a couple forums, and I have welcomed new people. The underlying intent was always "I'm really glad you're here, I hope you stick around, and do not under any circumstances feel like there is a trial period where you should be afraid to speak up."
You can get 100 "Welcome!" messages from 100 different people, and they could all have had subtly different tones and intentions, you would never know because it's text. So you're probably both right and wrong, depending on the person.
I think any social group will develop soft hierarchies, but on the internet they're particularly challenging because our previous experience is hidden to people when we join a community for the first time. I think that's particularly tough for people who are established in their existing communities, because on the internet our reputation rarely transfers over. We are all noobs until proven otherwise.
If a life long master carpenter joined a woodworking forum, there would be DIYers with 6 tools in their shed but a long time on the forum, who would talk down to them and question their advice. Everyone deserves the same level of respect and attention in discussion, but I feel a reputation for being knowledgeable on a specific topic is earned. This person might be "The Guy" for woodwork in his city, but online they are #WoodMan24 and no one cares.
For "old hands" where its just another forum it may just be an annoyance. Those who appreciate it as a chance to brag (guilty), often find more welcome opportunities for boasting in other contexts if they wait. Even then the perception of gatekeeping can negatively color the experience of the whole forum.
Some forums want to be limited in scope and membership, and this can be a useful tool for that. I tend to assume I will be among the unwelcome at any such division, so I don't participate in that kind of forum. Don't feel I'm missing much.
Basically the HOA of the internet.