I also like the keybase product. But when I see an ambitious, well-funded startup without a paid product or clear business model... that tells me I cannot yet trust their product, strategy or management team to endure. Next year they might be a completely different company, or might not exist at all. Since they haven't open-sourced their server, that makes it risky to rely on their products, because I don't really know what it is I'm relying on.

Signal in comparison is very clear about their goals, management and business model, and I believe are 100% open-source. That gives me confidence to adopt it now, even though it's a less feature-rich product.

I would love to see Signal adopt the Keybase identity-by-proof model, I think it's very clever and pragmatic.