i use il on nearly all my/our systems for file service.
indeed, given that two of them use /sys/src/fs as kernel
and one of those has a jukebox, that's nearly essential,
but even otherwise, i'm not convinced that il can't
be made to outperform tcp/ip on some network/transport types
(eg, because of Ildataquery), and compared to some code modules
that need to be kept compiling, it's anyway not all that big.

apart from il, i have used telnet (with the telnet protocol) over ILAP
and also in environments where /net.alt was indeed a distinct stack,
amongst others.