A partner at a VC will generally only vouch for one or two startups a year. They are responsible for allocating capital, not directing employees. Furthermore, the partner at a VC will generally not have anywhere close to 20% of ten startups (usually it's 15% to the fund). They have a draw off of the fund (which they have to raise) and they have a certain amount profit if the fund is successful.

I do agree with you that engineers (especially the first 4 hires) generally get the worst deal of all.