The whole point is that there are a number of solid VCs with small stakes involved. If it was operated by large investments by a small number of VC's, the mode

The whole point is that there are a number of solid VCs with small stakes involved. If it was operated by large investments by a small number of VC's, the model could provide problematic signals. Specifically, if those VC's get early and in-depth looks at these companies and choose NOT to invest, it would be a negative signal to other investors. By spreading this across a large number of VC's, this potential is diluted. The investors in Seedcamp are well known and respected investors... they're not "small time" with "very little experience". And many of them are long-time seed investors.