I am not sure how it works in PvP, but in PvE guilds are a purely social thing until you turn level 80 (and maybe also get yourself certain gear? not sure about it). Let me emphasize again: leveling players are useless for the guilds (except for creating a social atmosphere by talking in the chat), and their guilds are useless to them, except in the form of someone sacrificing their time and/or resource to do a favor to a guildmate. There are no perks for being in a guild (gathering nodes in the home instance maybe? but the guild has to be fairly developed for that). The boon-granting banners are limited in number, have to be operated by an officer, and are likely to be dropped for level 80 content in level 80 places. Guild events like bounty hunting are high level stuff, and while several people may gather together to do a dungeon with an entry level that a lowbie can qualify for, chances of that are slim, and despite the level nerf within instances, the lowbie will still be less useful to the group than another lvl 80 (because skills and traits), so anything you do with your guild will still be “you have to beg/convince people to be nice to you and do you a favor”, or “you are a great person and make friends who are willing to do you favors because you are a great person” rather than “you actually have something to offer (besides your great personality) and it is a mutually rewarding deal”. Sure, any player generates influence for their guild, but the amount of influence you make by logging on and playing solo is infinitesimal compared to what the high levels generate by doing guild events and instances, and buy with money.
And the single worst thing about guilds is that they are account-wide, and while you can choose to “represent” (essentially, “play as a member of this guild”) one of your guilds at a time, you are still visible to your guilds when you are online (on any of your alts) and not representing them. It is like having a friends list with no invisibility option, only you add people not one person at a time, but one guild at a time. Also, from what I’ve seen, guilds are typically jealous about that, and require you to play with them all the time you are online, or justify yourself to an officer. So, when shopping for guilds you can’t get away with playing a bit with these and a bit with these to see what they are like. Imagine looking for new work when your current employer gets an automated warning that you are seeking other opportunities?
Well, I am extremely socially awkward, and I don’t appreciate bringing too much or your real life into in-game conversations (especially when someone is lamenting how difficult their real life is – not looking for advice, just informing everybody how bad it feels for them – I get this feeling of being an unwelcome guest at a party, like everyone here is close friends between themselves (because IMO that’s where these laments belong) and I am just a random person whose presence nobody is even aware of). Neither “convince someone to do you a favor” or “quickly become buddies with people” works for me, so I think I’ll postpone entering a guild until level 80. Meanwhile, I am slowly collecting influence for a one-person guild of my own, and while it is of course painfully slow, I am ok with that as long as it is moving on.