Products too! Technology projects without an end-user often become vaporware because it’s impossible to make design decisions without constraints. A real end-user adds constraints. Constraints enable good decision-making. It’s much easier to answer a specific question (“is this a good decision for a bowser rendering engine”) than an abstract question (“is this a good decision for software”).

I don’t use Rust, but appreciate how it solves clear problems. I’m really impressed about the way key issues like packaging & distribution, documentation, and coding style/safety are addressed at the language level. I bet those features emerged from the need to address issues with the open source development model. Without servo, maybe those features don’t make it.