I got started around the time that EOTN came out, when the meta was already in place but still open to new theories as new skills were discovered or rebalanced. Everyone was excited about the game and about finding the best ways to play and succeed, and this was necessary because the content was difficult and you couldn't win with just any strategy, or lack there of.
Because of good replayability, the winning strategies became commonplace and cemented for each location. But I didn't have the experience of gtfo if you don't know what you're doing. People were helpful and instructive.
In GW2, it is a foregone conclusion that Zerker wins all, and there is neither the diversity nor difficulty needed to break people away from that. There is no discussion about strategy or anything related to talent in the game, except in few-and-far apart cases like Teq and the old marionette. That said, when something goes wrong, chat does go in the direction of gtfo, probably because we're spoiled by constant success and easiness in this game.
On a related note, you're very right about the lack of sandbox. This game is desperately in need of more skills to play around with.
The instructions I saw being given out were always along the lines of "Go to that corner" followed by something along the lines of "... Seriously?". PvP was straight up never mess up or gtfo/sit in the sister guild forever. This was before YouTube was filled with guides for everything too. Basically people expected you to learn quickly on the go or leave.
If you talk about lesser guilds then yes, they were more noob friendly but also failed a lot. I joined them to learn how to do certain speedruns, then migrated to more HC guilds which had high success rate.
I agree that people rage in global chat in this game occasionally, especially during summer/weekends when the school kids are active but consider this, most things in this game boil down to not standing in a circle or not damaging a clearly visible mob that takes long enough time to kill to realise that a 100 people are shouting at you in all the languages imaginable. Either that or there is a guy on TS giving a detailed explanation about how things are done i.e. wurms.
As for dungeons and fractals I never saw anyone rage, and I did all of them daily. People didnt mind showing where to stand, where to go, when to damage, dodge etc. In fact this is how I learnt dungeons.
Another thing is that HC guilds are sort of pointless in this game and boil down to a constant pissing contest involving legendaries, because frankly there's nothing else to a HC in this game. Large guild mission/WvW guilds are mature and overall fabulous. I was part of quite a few SFR ones, enjoyed the TS and the fact that the average age was above 25 with minimal drama in the chat.
This game is just super chill, nobody gives a ♥♥♥♥ hence good community.