Just stumbled upon this. myname(5) is not used by netstart(8) but by rc(8).
Maybe update the hostname(1) manpage for consistency with the manpage of
myname(5).

Index: bin/hostname/hostname.1
===================================================================
RCS file: /cvs/src/bin/hostname/hostname.1,v
retrieving revision 1.21
diff -u -p -u -r1.21 hostname.1
--- bin/hostname/hostname.1	24 Jan 2011 19:58:32 -0000	1.21
+++ bin/hostname/hostname.1	25 Aug 2024 07:14:45 -0000
@@ -30,7 +30,7 @@
 .\"
 .\"	@(#)hostname.1	8.2 (Berkeley) 4/28/95
 .\"
-.Dd $Mdocdate: January 24 2011 $
+.Dd $Mdocdate: August 25 2024 $
 .Dt HOSTNAME 1
 .Os
 .Sh NAME
@@ -53,7 +53,7 @@ or by supplying a
 .Xr myname 5
 file,
 which is used at system boot time by
-.Xr netstart 8
+.Xr rc 8
 to initialize the hostname.
 .Pp
 The options are as follows:
@@ -67,7 +67,7 @@ name.
 .Xr gethostname 3 ,
 .Xr myname 5 ,
 .Xr hostname 7 ,
-.Xr netstart 8
+.Xr rc 8
 .Sh HISTORY
 The
 .Nm