The more equity the venture builder takes, the less attractive the business. If the venture builder may need to be washed out, it puts early investors at risk of being washed out with it.
The less the people signing as exec founders on the investment agreement did to actually found the company, the less attractive the team. Evidencing the hustle to start the company is part of what sets a good founder apart.
It’s not so much that 20% of something is worse than 80% of nothing. It’s that the vehicle is compromised from day one.
You can mitigate this with traction but the model is a bit like trying to do a startup with one hand tied behind your back.