The VC-oriented financial model (that is, your typical startup) is fundamentally incompatible with Mastodon's non-profit financial model. As a result, very different choices around licensing, funding, and business structure are good fits.
Each tool has its use and serves its specific purpose. What works for Mastodon might not work for others trying to advance different goals.
Nobody should take VC money unless they absolutely have no other option.
The primary goal of a startup is to make money through acquisition or IPO, and the primary goal of business more generally is to make money selling a good or service. Grants and donations don't really fit into that, and isn't the topic of this whether or not to open source the code of a commercial venture?