So this is another thing I don't get. Why don't startups just open their product up for everybody right away? Are they afraid users might come by the millions a

So this is another thing I don't get. Why don't startups just open their product up for everybody right away? Are they afraid users might come by the millions and crash their servers, because their product is too much awesome to be let unprotected in the internets? Getting users onboard is hard, you should actually want them to come and use your product.