Eh, I think multiclassing should be in the game, but I wouldn't call it essential to building a balanced four person party. Its not really all that strong in 5e, and you are very likely to lose more than you gain unless you are extremely disciplined with your choices.
I certainly did not miss multiclassing in Solasta.
I do miss it a lot in Solasta, and that is one of my only two major complaints about Solasta, alongside the party size of four. And btw, I also see the lack of multiclassing as the only drawback of PoE1.
