That's not really true until an equity round these days. Companies who raise seed rounds on SAFEs and notes often avoid having a board. In the portfolio of my firm, that situation accounts for just over half of the initial seed investments we've made in the past five years.

Forming a board is an investment from both sides. It takes a lot of work to be a director or even an observer. At the earliest stages (pre-A) VCs are much more willing to keep it informal and avoid the distraction.