Divine sources (gods, mostly) can only grant spells they themselves can cast; divine magic more about being a conduit than a caster.

Warlock Patrons are more akin to mad scientists grafting magic onto the warlock’s soul. Sewing a giant crab claw on someone does not give you yourself a crab claw, and it’s kinda difficult to perform that operation yourself.

If that goblin is the last enemy, it’s braver than any goblin on Toril.

Very few battles are fought to the last warrior. When the battle is basically over, enemies would know this and flee.

Giving a player something then inventing an arbitrary rule to nerf that thing is indeed stupid.

To point out how stupid it is: “While you are riding your drake, it can’t use the flying speed of this feature.” Nothing says it can’t pick you up by the shoulders, or that a small party member can’t ride it instead.