By Nicole Perlroth April 20, 2012 3:02 pm April 20, 2012 3:02 pm 10:46 a.m. | Updated Added link to Ben Horowitz’s blog post on the subject. 3:53 p.m. | Updated Added comment from Ben Horowitz of Andreessen Horowitz. SAN FRANCISCO — Marc Andreessen, the Netscape co-founder who went on to use his considerable wealth to finance scores of Silicon Valley start-ups, is regarded as one of the smartest t