In my experience, the majority of new players that quit are the ones that don't know anything else to do other than shovel brahmin shit, they have not obtained a tent yet, and have a crappy build.
The problem isn't that their build isn't a "PvP-only build", their build lacks the necessities of playing; they, for example, might have 5 Luck, or 5 Endurance, or 4 Charisma, or multiple combat skills, or have a skill like Barter tagged.
Of course, there are many knowledge resources out there, but obviously a lot of new players do not read them. Laziness might be the reason for some, but others are just ignorant of how to get the information. I'm glad to see that the developers put a note about Opera's character planner as one of the headlines, though.
There needs to be more information, for example through dialogue, in the actual game. Almost every player that is starting talks to the NPCs in the three respawn points. These NPCs could give more tips on how to start, with still keeping the environment of the game intact. Something simple like "Oh, by the way, some wastelander was able to put up a decent tent using 10 or so brahmin hides he found...". Might be a bad example, but the point is there needs to be more tips in the actual game.
Speaking of brahmin hides, the most populated protected town is NCR, but around NCR, new players have a very, very difficult time obtaining brahmin hides. Okay, they read the wiki, and know how to get brahmin hides, but where are they? There are encounters on tiles bordering NCR that do have brahmin in them, but, at least for me, these encounters are quite rare. There needs to be more frequent brahmin encounters in towns closest to the three original spawn points. There are tons of brahmin near Modoc, but a new player spawning in NCR isn't going to know that, and isn't going to suffer to get it. They'll just quit.
Traders could also provide more brahmin hides, as a way to get them without having to use combat skills that most (unless they are unarmed) new players have almost none of.
An updated in-game list of commands would also be convenient, or at least in the F1 menu, link to the wiki's page.
This next idea might be a little odd, but there might also be a "random tip" as the game is on the title screen before you log in, similar to F3 and NV (except not during loading times, since this game doesn't take nearly as much RAM to load). It could be on by default, but easily be turned off in FOconfig.
Many people find the current travel speed to be very boring, but that will increase post-wipe, at least. And for the problem of encounters the same person X amount of times, I agree there should be something that let's you not encounter them on the same tile/encounter until X amount of minutes have passed. And since the world map speed is going to increase, the time you are on one tile will decrease, making this less of a problem post-wipe.
Just some of the ideas on the top of my head that I thought of to help noobs not ragequit so easily, and actually try to enjoy the beginning of the game.