.NOTPARALLEL doesn't seem to work as shown in the documentation

Greetings,
I am trying to learn make, going through the documentation and even writing
a repository containing examples copied, extrapolated or commented from the GNU
make docs <https://www.gnu.org/software/make/manual/make.html>.

In Section 5.4.1
<https://www.gnu.org/software/make/manual/make.html#Parallel-Disable> when
running the .NOTPARALLEL selective example (reported as an attachment) I
noticed it would run sequentially in all cases, contrary to what the
documentation states.

VERSION: GNU make 4.3
OS: Windows 11
VM: WSL
DISTRO: Ubuntu 24.04.1 LTS (therefore I imagine it is posix-based)

Best regards,
Gabriele