Why do photographers still use light meters?
I am not a lighting guru by far, just an enthusiastic hobbyist.
For me a light meter is very useful for studio work, where I always shoot manual. It allows me to prepare and have a better control over light before the actual model walk on set.
It saves time for my model / client and then during the shoot all I have to do is a few minor tweaks on the lights / strobes.
Using the build-in light meter or taking a few shots and checking the histogram can help but a good light meter is the right tool for the job.