That is probably a mistake, it is found only in one example on that tutorial. All other examples have copytruncate without the create option. Also logrotate man page states that It will be actually ignored:
copytruncate
Truncate the original log file to zero size in place after creating a copy, instead of moving the old log file and optionally creating a new one. It can be used when some program cannot be told to close
its logfile and thus might continue writing (appending) to the previous log file forever. Note that
there is a very small time slice between copying the file and truncating it, so some logging data might
be lost. When this option is used, the create option will have no effect, as the old log file stays in
place.
Regarding maxage, I think it can be useful for example for logfiles which can be empty for few rotation periods (days/weeks/months) — if you use notifempty, empty logfile will not be rotated, so you can have too old rotated files still in place.