His point is that for a level 1 spell, a 10ft flame surface that does 1d6 per round (on a highly escapable surface, DEX ST for to negate after the initial round, isn't by any means game-breaking for the cost of a level 1 spell slot. Considering that Burning Hands is a 15 ft cone for 3d6 DEX ST for half. I assume calling it a 8d6 DEX ST save-for-half fireball is strictly hyperbole.
All this means is Larian is deviating from 5e core rules - which we all know already.
Would it make you feel better if I'd referred to is at 'fireball-lite''? It doesn't change the fact that the change takes what is supposed to be a spell that impacts mobility, and turns it into an attack spell. When combined with the broken sneak mechanic, you can cast grease in a surprise round from 60 feet out, and immediately cast firebolt easy as an opening salvo at level 1. There's no comparison to burning hands which at least requires you to somewhat risk being close to melee combat to offset the damage it does.
I think there is a slight misunderstanding here. I am in NO WAY arguing for Larian to implement this. No more BG3 surfaces than there already are. Honestly, I don't know anything about BG3's implementation of grease...I assume it catches fire and explodes, knocking people prone, dealing instant fire damage, and then catching them on fire?
I'm arguing for grease catching fire in tabletop. Or, at least, saying I'd rule that my games. In tabletop, given that most DMs would prevent a "broken sneak attack mechanic," its effectiveness is way lessened. If it catches fire (not explodes) and deals a small amount of damage (e.g., Dex ST for 1d6 fire damage) to people, then I don't think that's overpowered.
In your example where a torch is placed down first, then the grease immediately catches fire and would not make enemies fall prone. Basically it turns Grease into a ranged Burning Hands with ~1/3 the effectiveness and a smaller area, which I'd argue is a very poor use of a 1st level spell slot. Magic missile would do more damage.
