Those who are either too cheap, or just plain starving students, but still want to add extra camber without paying for a longer
control arm. Adding negative
roll center adjusters, NRCA for short, is as cheap as you can be. Being a suspension component that is subjected to all kinds of environments, i've noticed on some customer's cars, that removing the bolt can, at times, be difficult. But in some rare cases the blocks threads tend to strip. I suspect it's all the water and dirt that tend to accumulate in the are shown above.
To combat this, I just add a bit of tape over the holes to seal. Simple yet effective, though probably some better is more appropriate but I was too cheap at the time to buy it.