The first people become the stewards.
People care about what they help shape.
What early participation gives you
a voice in what gets built first
a role in how the shared record is governed
a seat at the table when the stewardship model is written
the chance to shape the product around a problem you have already felt
What it asks of you honestly
Early participation carries no ownership of the whole, no title, and no expectation that you quit your job. It carries influence, and influence is the scarce thing here.
The real reason
The first people become the stewards. The shape of the community is set before the product is finished, and it is set by who is in the room when that happens.