you mean "isn't"? Though there is no indication that a lot was invested, so doesn't give you the measure (my comment was about the availability of resources, not of their actual use)
It's done on the majority of the OpenBSD base system, as well as important ports like Chrome and Firefox. Linux also has the parts to do this, though it's more fragile and complicated.
To be clear I have a much higher standard for what is acceptable than that, you really need to consider software that a hundred million people are going to use
