I think those multipliers can overstate the encounter difficulty in some cases; perhaps edge cases. The goblins have 4 HP, so in most instances, they'll go down on a single hit. So their numbers drop quickly. There's no way the ambush with four goblins is beyond hard; and really, I'd say it's between medium and hard. They should expect to have to heal up after the fight and in rare instances, things could go very bad.
I have to disagree with this one a bit.
The four goblins are easy to hit and kill.
But, they are not easy to find.
They have a special ability to hide every single round (in the woods, attack, move, hide). If the DM is rolling just a little bit well on their stealth checks, it can turn pretty nasty pretty fast.
For many games, a surprise round will occur. Some PCs surprised (all of them in my run of the encounter), some not. That's a round with four hidden advantage attacks by the goblins. If they focus fire on the nearest PC (which makes sense), then one PC can easily go down in the surprise round and a second PC might be injured before most PCs can even act. All four of those attacks have a good chance of hitting due to advantage. In round one, the PCs have to go find the goblins. Sure, one or maybe even two Goblins might have rolled crappy for their Hide attempt, but that just means that the Goblins that rolled well might not even be attacked in round one. So again, another round of advantage attacks.
I suspect that some of the TPKs reported for that ambush were caused by DMs running the NPCs exactly how they are stated combined with a few bad rolls by the players and a few strong rolls by the DM. The problem with first level PCs is that they have few of the standard recovery actions that higher level PCs have. They do not have the hit points to absorb a lot of abuse combined with few options to turn the tide of battle like at higher levels.