The primer says that there are no truly bad matchups, that the advantage of this deck is that no single card really shuts it down.
I don't know if this has been addressed somewhere in between (at the very least the primer needs updating), or maybe it was missed because the offending decks see very little play right now. But with Jund now a DTB, let's not forget about this card:
Blood Moon.
With an 8 Blood Moons.dec opponent (Dragon Stompy, Imperial Painter, etc.) dropping Blood Moon turn 1 on the play, Jund basically scoops. You have 3 basics, high colour requirements for your spells, and a very low probability of drawing the right basics naturally if you don't have a fetch to crack in response.
Lightning Bolt and
Grim Lavamancer alone are not gonna get you there, although they do at least kill
Magus of the Moon if opponent has not already dropped
Chalice of the Void@1.
If you're on the play, you can drop DRS first or hope to rip their Moons or acceleration with turn 1 discard. But if they have 2 moon effects, topdeck one later, or blow up DRS, then you're still in trouble. Once Blood Moon is in play, your ways to kill it involve both black AND green mana (Abrupt Decay, Maelstrom Pulse, EE @ 3). This means that DRS alone does not give you enough colored mana to blow it up. You would need BOTH singleton basics or DRS and a basic swamp/forest. You could try to use DRS just to generate colored mana to cast other spells, but you will eventually run out of land fodder (no lands will be hitting the GY with Moon out) and your deck is majorly slowed down by that restriction. So killing the Moon is a must. If you're on the play, you can go Turn 1 fetch basic swamp and cast DRS, safely having Abrupt Decay mana up as long as you don't see removal or graveyard hate. But the bottom line is that even if you get to go first and be proactive, that card is still a headache.
BUG, RUG, Bant and other 3-color lists with flimsy manabases all run Force of Will, so they can better interact with turn 1 Blood Moon. This may be why Blood Moon is not considered a legitimate threat to those decks. But a deck with only hand disruption has a much harder time holding it off.
I'm not saying this is a reason not to play Jund; I'm just saying I think Blood Moon deserves a nod in the primer.