Yes, you're right that it generates garbage, but that's besides the point. The point is that a huge number of programmers, especially in the 90s and early 00s

Yes, you're right that it generates garbage, but that's besides the point. The point is that a huge number of programmers, especially in the 90s and early 00s would argue for UTF-16 on the basis of it being a fixed width encoding in practice. Maybe they didn't know that it actually wasn't, or they knew and didn't care because they never had to deal with anything outside the BMP. The overlap between Windows programmers producing software for e.g. in the U.S. or European market and those that would have ever encountered a non-BMP used to be tiny until emojis came along. So yes, while not in theory, in practice you could get away with treating UTF-16 like fixed width encoding like UCS-2 for a huge number of applications where you could reap the benefits of constant-time chars(str) and charoffset(str, N).