Maybe we have different definitions of thought but there's definitely not a lot of in-depth analysis and due diligence in most deals, as that's how portfolio theory and sufficient deal flow is attained.

What you're talking about with IPOs is not quick or easy, and definitely not guaranteed in any way. Taking a company public essentially counts as an exit for most funds, and if it was that easy to just sell up everything then the entire VC field would look different. That process is more for private equity and banking firms who maneuver through financial engineering rather than early and mid-stage VCs.