A major part of the problem with Tribal governments is that they have an unexpectedly easy access to mercenaries. That's because Tribal governments don't have to pay upkeep in money, instead they pay in Prestige. This leads to a situation where "with one hand" you can finance your men-at-arms with Prestige, and "with the other hand" you can finance your mercenaries with gold. Cheap gold can be used to get a quick trump card in wars where you are a couple of thousand soldiers short of pairity with the enemy alliance or, if you already have pairity, to get a crushing advantage. Thus by winning the wars you buy Prestige with gold, and then it becomes self-reinforcing...
Feudal governments on the other hand, need to pay upkeep of their men-at-arms and the contracts of their mercs in the same currency. Go figure.
With about 200 gold being able to buy you around 1500 quality mercs for 3 years (which amounts to about 0.3 gold per month, wtf do they eat?) and the principle is pay and forget instead of monthly upkeep, a Tribal government can raise big numbers very easily. Due to the combat "balance" numbers are still very much the deciding factor in combat. Nerfs from terrain and counters based on unit types are not doing enough (although they are a good idea), and men-at-arms are not wiping the floor with levies enough, at least not in the early game. And if this ~200 gold was easy to accumulate if you have enough direct holdings, even in the Development-poor area of north-east Europe where I was playing, it will only be easier in areas with better development.
CK2 was already about the larping / house rules, and so is CK3.
Yeah, but first, if a game is so much lacking in challenge without house rules, this is evidence the balance is broken. Which, in connection to what I was saying previously, is not helped by the super-large world map.
And second, if this problem persists in the next game of the series, that's a major design flaw not being addressed by the game devs.
I anticipate the argument "well, you picked one of the strongest/easiest factions to play as, so what did you expect", but that's not an excuse either. If one of the most played and historically interesting factions is also one of the most broken ones, then where does the problem lie again?
I think CK3 made it more difficult to move on from gavelkind / partition for feudal cultures - in CK2 you immediately had feudal elective which was serviceable until primogeniture.
That's true, though there are still ways to circumvent the feudal breakdowns. One of the methods shown by youtubers I think is even a bug - it involves changing your realm capital to a county while this county is not part of an existing duchy title - it's still a de jure duchy capital, otherwise you wouldn't be allowed to set the realm capital there, but the key is that the duchy title has not yet been created. Then all the counties in that uncreated duchy will be sent to your Player Heir, in addition to those that were coming to him from the previous realm capital.
What I was thinking of doing is to install courtiers with hooks as vassals of my son who will swipe my titles, and then use them as moles against him, but I think the weak hooks are not inherited. Bummer.