I'd like to say this is true, but I think in practice, you want early engineers to have the right technical + mental frameworks around good software development

I'd like to say this is true, but I think in practice, you want early engineers to have the right technical + mental frameworks around good software development practices, and the current implementation may not reflect this (false negative). It's a good to have, but not a top concern imo. One of the startups I worked with didn't have "good" practices just like what is listed above, and it took a while to get there. The thing is, we're still pulling quite healthy numbers, and we have paying customers. What made it bearable was our engineers knew what needed to be done, and had the technical chops to get there. You'll probably want to avoid very elitist engineering cultures that aren't open to what's considered good practices. Many successful startups run on the shadiest software architecture in the early days, but market pulled product out of the startup. Today, they have the engineering resources to make it a lot better.