I was about to write that this needs an extra decoding step because an addressing mode that uses a base register, a scaled index register, and a byte offset is

I was about to write that this needs an extra decoding step because an addressing mode that uses a base register, a scaled index register, and a byte offset is a very CISCy thing. But of course with 0-based integers, it's no longer necessary to decode the index, so it's probably a wash.