Sure, you don't see it. I do. Different tables and different experiences and all that. The players I have played with for over 40 years are min/maxers, and all about the power. If they can multiclass to boost slots to, say, Smite, or stack up Ability Score bonuses for whatever, or to do wonky combos with familiars, darkness, devilsight while combining that with a rogue's sneak attack, etc., its pure gamism (in my opinion, your experience may vary, etc.).
Yeah, I see that too. But my point is those guys are still less powerful than a single class Wizard, so I don't see the big deal with it.
Sure you can build a better Paladin getting more slots to smite and a familiar to give you advantage and a couple fighter levels to action surge .... and you are still less powerful than a Wizard and TBH even less powerful in melee than a Wizard that is optimized for melee.
Like in your example about your getting lost in the jungle. So, the only way the game could progress is for your character to all of a sudden be able to become a ranger, complete with "favored terrain: jungle" (how convenient!). I mean, great that that worked for your table, but that is jarring, and shouldn't be necessary. Why are hired guides so bad at "guiding"? Is everything left to the whims of the dice rolls vs ability checks? Why can't the environment, or the guides, actually do what they're supposed to be able to do without constantly getting lost?
I would not have been necessary if we bothered to get a player with a good wisdom and proficiency in Survival.
This can depend on the kind of table you are at. Some tables people get together and choose what to play in "session 0" based on roles and on such a table it would not have been a problem. We would have had a player with good Wisdom and proficiency in Survival .... or maybe even a Ranger at level 1.
This wasn't one of those tables though. This was more of a come as you are game, everyone show up with your character and no "party planning" before we headed off into the dungeon. I think in session 1 we had my Rogue, two Wizards and a Cleric. Multiclassing let us get the skills we needed as part of the story.
I'd be annoyed at "having" to dip to make the campaign actually work. But I'm glad you made lemonade.
For me personally, I would rather let the game drive where my character goes than have a role defined ahead of time - "you're the healer" or "you're the tank". I actually prefer games like that. That is not to say I don';t have an idea of what my role is when I start, but it often is not set in stone.
The TOA example was admitedly extreme, but I am doing that sort of thing regularly.
In the game I DM'd, session zero was about a FR campaign set in 900 DR, in the Moonshaes, with a very dark ages/celtic/mystery/low magic type setting, with less murderhobo, more RP, total sandbox, etc. All agreed upon by the players, and then two of the four go about multiclassing into some kind of spellcaster, except for the arcane archer, and fighter. So we had Sorcerer into Twilight Cleric, Rogue into Warlock for familiar stuff, etc. Completely against theme, completely at odds with session zero agreement, etc. All for the perceived ability to want to "win" DND by a couple of players at the table. I also realize that can happen in any version of DnD as well. But 5e makes is easier, again, in my experience.
I am guessing this game was point buy or standard array right? The best way to curtail this IME is to have people roll abilities and then have it so those rolls are fixed to an ability (you roll strength, what you get is your strength you can't move it to Wisdom, you roll dex, what you get is your dex .....). That does not hard limit your classes at all (although it can make it more difficult) but it severely limits your multiclass options.
Anyone who wants to win 5E really, really should play a Wizard. Trying to "win DND" without a Wizard is like trying to win the Indy 500 with a go cart. I don't care what multiclass combos you come up with an optimized Wizard is still going to take them to the woodshed.
And the single class advantage is only really a thing when you're playing up into the teens and close to 20th level, where the lost levels to MC might matter. Most games I've been in or run cap out after years around level 12ish or less. So the MC "penalty" isn't really one at all considering the additional benefits you can just bake in.
It is not a single-class advantage. It is a single-class Wizard advantage specifically.
Regardless, this is not really true IMO. In a 1-12 Adventure, multiclassing a character before 5th level will typically make 5th level itself much worse due to the substantial power increase that occurs there. The only exception to this is a multiclass Warlock that relies on Eldritch Blast. Just about every other character combo will be better with a single class 5th level character. Also 4th and 8th level will generally be worse for a multiclass character as compared to a single class and 6th, 10th and 12th level will sometimes be worse depending on what classes you are talking about. That is half of your 1-12 adventure.
And yes going from level 2 to level 12, I would put an optimized single-class Wizard up against anything at all at almost every possible multiclass combo at every single level in there. I always multiclass, but I can't think of a single build from 2-12 where I would be better as a multiclass character than as an optimized single-class Wizard.