We are in 100% agreement. With a note that if there are 34 goblins on the field you grabbing that one spellcaster doesnt matter as much because youre about to get 33 arrows in your face while you stand in acid getting -2ac while also being on fire.The reason someone is "key" is because they are a high value target. Every time you add another head to the initiative, everyone else gets a little less important. You can still have someone whos gonna ruin your day and you want to stop him, but at a certain point thats delaying the inevitable, the swarm youre fighting is too powerful as an entity to make reducing it by even a powerful 1 as important as your typical D&D encounter would. I say typical by using the D&D rollable encounter tables that they publish with their modules to give DMs playtested encounters that are area and level appropriate. Adjust at DMs discretion per what you feel justified given the players at your table. This is a playtest, they have posted maps about where peopel are dying, they are testing encounter lethality. They don't think it is perfect either and Im confused why people are defending it when Larian very reasonably could say "99% of our players die at the goblin camp, we have changed it". Yeah, its too hard. They probably will. The staunch defense of that encounter for what is supposed to be the beginning of a huge game where im sure youll get your ass handed to you later is just bizarre to me right now.
I don't get your example. In BG3 there's a couple of fights where you are forced to deal with an horde, and the game provides you with ways to deal with said hordes easily enough (you don't have fireball yet... but you have flame spells and loads of explosives...). Goblin camp isn't an hard encounter, it's just terribly boring because those easy to kill goblin "moving targets" and their lumbering ogre friend take a long time to die as there are so many of them.
The game actually has some challenging encounters and they are not about hordes. One is in the Hag's lair (the party of 4 masked servants), the Duergars can be problematic if you can't focus the right targets at the right time, facing the kuo-toas without proper positioning may also be diffcult and the beholder fight can also be complex as long as the spectator manages to build itself enough servants. None of those encounters is an horde encounter though.