I'm currently having a similar experience in WotR.
Charisma classes are very hard to play in this game for someone new to the Pathfinder ruleset, so I rerolled as an Assassin (easiest class to play, massive damage output), focusing on Long Bows.
Upside: fights are now easy to understand, no struggling with massively underpowered spells (are they serious about only doing 1D4 damage with a damage cast?).
Downside: intense problems with the story because of lack of persuasion and, in this case, also arcane knowledge. Party members are not that helpful, either.
I think game designers need to reconsider this aspect of RPGs. We need some tools to allow for a more "diverse" experience in games, not just "either fight well or talk well".
Which is also why I prefer playing the Warlock in BG3... Charisma opens the story and enables player agency.
I think you mean a slayer because the assassin is useless. Fortunately, it's not so bad, it's easy to get quite a decent value of persuasion and perception on the slayer.
Half-elf is very useful here because of the added bonus.
Arcane knowledge is not too much of a problem because there aren't many checks and then you will unlock a broken companion who can handle most of the checks in this game.
Yes, could be the slayer, I'm playing WotR in German and the class names are QUITE confusing.
Actually I'd prefer to play the charisma based caster class, because I would like to be "Warlock for Calistria" (sounds like a political movement, haha), but why play a caster who is actually only using the crossbow anyway...
Seriously disbalanced if you ask me, but maybe there are a few things that I need to learn before I can start casting spells in my next playthrough.
Also I met the "broken" companion. I actually want to take this one with me, because I like broken companions, and maybe she will see that the forces of Chaotic Good can be a good alternative to her atheism, because us chaotic good folks never
burn witches or do other nasty things only the actually evil "lawful good" folks are known for
.

However, back to the topic and why it's here:
It's more of a philosophical discussion, I know... but I still remember me working out my first "fully viable" party composition for my first D:OS2 playthrough in Excel with the goal to get me through levels 1-9 quickly and painlessly.
The question I'm still asking myself is: is this really how RPGing should work?