Each spell of the same level being just as good as every other spell of that level, I don't think this has ever existed in any DnD game, or even in PnP.
Players end up creating games where some spells are banned, or you must use the spells the DM says, or just playing weaker characters for fun - this works in the context of PnP because you can make the game as challenging as the builds you are using.
In a video game, it is always the same content, so if one spell is clearly superior to another, no one will use the weaker one unless again their trying a self imposed hardcore run or something.
Regarding chain lightning, in BG2 it was a bottom tier spell, one of the lowest damage spells by far, and every damage spell was outclassed by level 3 skull trap. Same with Delayed Blast Fireball, simply a waste of a level 7 spell slot. Meanwhile in BG3, chain lightning is mega OP top spell to have, meanwhile enchantment and illusion spells beyond the hold spells are just trash.
