Lol, that's because it's about ARMv6. She even points it out in Part 1 or so (not sure where but I saw it somewhere). If you wanna include all differences of ARM that would be a long tutorial.
I think you'll find the only reference to v6 is where the register names are explained, e.g. <= v7: r0, r1, etc. This is another thing it gets wrong, i.e. A64 registers can be x0, X1, etc, but also the lower 32 bits can be addressed via w0, w1, etc. http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc....
Page 1, right before the table cross-referencing ISA with ARM family. "The examples in this tutorial were created on an 32-bit ARMv6 (Raspberry Pi 1)."
Easy to miss, particularly if you are scanning through.