I started using rifle scopes over 50 years ago. I recall many times I could see and animal but not the reticule. Illumination would have helped with those tiny, thin crosshairs.
I now have many top end rifle scopes. With todays reticules I have no use for the illumination. Remember, it only illuminates the reticule which is never hard to see if you have light enough to see the target, you can see the P4f or H59 reticule. Illumination actually hurts your low light vision by constricting your pupils which obscures a target in a dark area. Most of my scopes have illumination but I also use many like the S&B Ultra Short that don't have it. I never use it even when I have it. And I do a lot of low light shooting.