> To be fair, UTF-8 sacrifices almost nothing to achieve backwards compat though.

There were apps that completely rejected non-7-bit data back in the day. Backwards compatibility wasn't the only point. The point of UTF-8 is more (IMO) that UTF-32 is too bulky, UCS-2 was insufficient, UTF-16 was an abortion, and only UTF-8 could have the right trade-offs.