This isn't my experience at all. Most "security experts" I know are familiar with the so-called "CIA triad" and understand quite well that the "availability" part is just as important as the "confidentiality" and "integrity" (i.e., the "not compromised") parts.

If one doesn't, well, she isn't much of a "security expert" after all, is she? Firewalling off TCP port 80/443 at your perimeter firewalls isn't a very good solution if you're an e-commerce company selling your product on your web site -- and the "security experts" know this.