I cannot believe they thought it would be ok to go Wizard+Cleric+Sorcerer+Bard multiclass and still cast full caster spells in 4 class, there's got to be a catch.
Yeah, I'm with this stranger. There's gotta be more to it, right?
It's called still being limited by concentration, the limited number of spell slots, the limited action economy, and the fact you're not going to get all of those stats to 20.
To be fair, only one of the qualifications you listed isn't heavily mitigated by something in the game.
- # of spell slots isn't necessarily a concern because you can long rest every fight or two*.
- One of Larian's early goals with BG3 was to expand the action economy to make earlier levels more fun (for martials particularly, which is a fair criticism of 5e). BG3 casters have numerous ways to get additional actions for leveled spells, both of the regular and bonus variety.
- It's not infeasible to get three stats to 18, possibly higher, through a combination of dump stats and magic items that set certain ability scores to X**.
I haven't seen any mention of a concentration-bypassing item in BG3.
*Depending on how Larian balances the prevalence of food supplies, and how many dungeon-y areas prevent long resting.
**Depending on the exact prevalence and slot requirements of the stat-setting magic items.
