Comment by umanwizard

Well, I am. MacBook on a home internet connection in Arizona. Using IPv6 by default without me having ever had to do anything special to configure it.

You are simply misinformed. Either your setup doesn’t actually support IPv6 (or it’s much slower than IPv4 due to something being misconfigured), or you turned it off at some point, or you’re making a mistake in how you measure it. Because IPv6 is used by default on systems that support it. You don’t have to take my word for this, you can google it or ask someone else to try it.