I wouldn't call assembly 0-based. Sure, the zero flag is convenient for branching on zero when counting backwards but what makes assembly 0-based apart from that? I'd say having a pointer to the first element of an array is pure convention and you could as easily point it to the imaginary element before, similar to how the program counter always points to the next imaginary instruction on most architectures.
The offset addressing modes all start from zero. You could hack around it in some places by storing the pointer to an element before but that's clearly going against how it is intended to be used.
For example if you have an array that you cast between different sized types (e.g. uint64 to uint8) then you have to change the pointer value!
