Presumably bad ROI
That's a big presumption isn't it?
It was accepted wisdom that you had to pick individual stocks until Vanguard popularized the index fund and now it's accepted wisdom to do the opposite.
It's one thing to pick up stocks of market leaders (which may or may not be having a good time this year around) and another thing is to pick stock of noname startups from the bottom of the pile. Far more risk.
There's a reason early stage VCs do dd, it's to weed out complete garbage which wouldn't ever possibly do any return. Probably it is not worth scaling that and easier and more measurable to just stick such big amounts of money into later stages.
why do they need to make any decision at all - if it's like lottery, why not invest in all 4000, let it run wild? The survivors after their money runs out are the good ones.