As a Python person, I'd say it's not so much about "power" as it is about correctness: equating "sequence of bytes in an encoding" with "string" is the source o

As a Python person, I'd say it's not so much about "power" as it is about correctness: equating "sequence of bytes in an encoding" with "string" is the source of a lot of (potentially hard-to-find) bugs and annoyances. So the approach of saying that a string is a sequence of Unicode codepoints, and that there's a separate type to represent sequences of bytes (plus codecs to handle translating between the two types), is a better way to do things. And I think this is borne out by the sheer number of articles that have to be written to remind people who use "strings are bytes in an encoding" languages of just how many assumptions they end up making that turn out to be wrong (most of which boil down to expecting bytes-in-an-encoding types to behave the way Python's string really do behave, as sequences of codepoints rather than as sequences of bytes where there may or may not be one-to-one-correspondence between bytes and codepoints).