OK, without knowing who you are, I am in the dark (is this a new incarnation of Eadon?) But neither my original post, nor (AFICT) any previous post mentioned AIX.
It is a very tenuous link saying that because OS/2 probably had a CLI for configuring networks, that AIX was a suitable comparison, merely because IBM wrote both of them. Whereas, I do comment about AIX, which makes it much less tenuous. Maybe I should have said someone who knows of me - possibly in these forums.
As far as I am aware, ifconfig does not, on any UNIX, make persistent changes to the system. What you may actually have fallen over is the fact that AIX does not even enable the interfaces by default until they are configured (they default to a down state, but can be brought up by a suitable command - cfgmgr in this case). I assure you that it is possible to bring the interfaces up to a state where you can use the standard ifconfig type tools quite easily. In fact, IBM provide a sample RC script to do it, not that anybody really uses it.
You get used to a particular system, but in my experience, moving on to a new platform has always required you to actually learn about the foibles of that platform. If you expected AIX, Tru64/Digital UNIX or HP/UX to work exactly like SunOS (showing my age), then you would be disappointed. And before I became mainly focused on AIX, I used a significant proportion of the UNIX systems out there, so I am pretty certain of this.
It was always the case that moving onto a new platform, the first thing you found was the management tool, whether it was SAM for HP/UX, sysadm for DG/UX, admintool on Solaris (before they removed it) or SMIT for AIX. Relying on ifconfig as the primary configuration tool is not wise, as different UNIXs use the arguments differently (and have significantly different syntax).
My Solaris knowledge is very rusty (havn't logged on to a Solaris box for over 10 years), but from googling a bit, to persistently configure a network interface, you need to use the oh so standard dladm command! Or edit a bunch of files.