Tech investors don't ask for business plans because they know they're worthless. In fact, they're worse than worthless, they're a possible negative indicator of success. If anything, they've been burned by the companies that did have them. Polished MBAs with great business plans start stuff like Pets.com and GovWorks. Nerds with no business plans start Google.
I don't dispute your experience but would caution that 2005-2008 may not be a guide for 2009-2012