"Single player games don't need to be balanced" is another absurd thing people say without further thought.
Magic isn't an excuse to do whatever.
The world has to be faithful to DnD 5 rules and Baldur's Gate (Forgotten Realms) lore, doing some slightly changes to preexisting rules to make the experience better (like making rangers better, as they're lacking in the PnP DnD 5, as an example).
