A benefit of being a developer is surely being able to create whatever you want. If you claim that "Baldur’s Gate 3 is an expansive, cinematic, player-driven RPG based on 5e D&D" then it is a claim that you are not making whatever you want, right? You are accepting something that is already established. In particular, this means you are accepting the rules of 5e. Fifth edition is its ruleset, right? Without those specific rules then what is 5e?
Well ... yes, but actualy no ... or at least not exactly.

This topic was repeated so many times around here i almost feel like spambot for bringing it up again.

But let me repeat myself:
(just note that im meerely stating my own opinion and if you disagree with me that is totally fine ... but remember that you asked

)
Its all matter of perspective.
I mean if you promiss that your game will be "based on 5e" ... you indeed should "base" it on 5e.

Wich is i believe the part you wanted to hear, now for the less popular part:
The important question we need to ask, to underatand it corectly is: what does "based on" even mean?
I mean if you would just litteraly transcript every single rule ... its no longer "based on" ... its just "5e" ... pure, or RAW if you wish.
So from this perspective i dare to say that its quite safe to presume there have to be differences.
And that is exactly the place where developer vision come to play.
In ideal world developer and player vision would be identical and everyone will be happy as a flee. ^_^
But that is not the case is it.

I dont think there is need for some heavy argumenting here, all you need is just read few topics here and it should be clear that there is no unified vision on our side ... therefore its litteraly impossible for Larian to meet our expectations.
Now every time you hear Swen say in some interview that some rules "dont translate well in CRPG" that is conflict between 5e and their vision he is talking about.
And it can mean anything on scale between "there is no way to implement some rule" (or there may be some but we just dont know how) to "we tryed this rule and we dont like the outcome".
Sadly (but understandably) we will mever know both wich case it is and wich rule is he talking about.

That said there is one more important question!
And that is: How much can rules be alterned and game still be concidered "based on 5e" ... and that is the very core of this topic.

Lets be honest witch each other for a second ... we (players) are Gandalf the Grey on king Théodens court ... meaning we have no power here.

Best we can do is offer feedback, suggestions and ideas ... and then hope someone in Larian will see that and think "that actualy sounds better".

And why? Bcs we are trying to persuate Larian that our vision is better.

And why is that? As i said ... bcs its their vision what matters in the end.

Personaly i believe that in full extend (and it is a little at absurdum) you can create basicaky anything and stil claim its "based on 5e DnD" ... on scale from 8bit pokemon to open world real time MMORPG.

Bcs as long as there is any relation to 5e it is "based on".
