First, there's an asymmetry in effort; it costs them very little to ask for things (keeping them informed on progress, having due-diligence calls with their network, &c) that can cost you a lot to provide; second, in exchange for their minimal efforts, they get optionality, which negates FOMO, which is the real reason they invest.

Maybe things have changed in the last couple years, but for first raises for companies, this wasn't like, "a thing that happens sometimes"; it is the normal, standard behavior of VC firms. People who are good at raising have strategies for dealing with it.