Anyway, re: the substance of your post--I've used a few email services for the handful of small web apps I develop. I'm currently on Postmark and I really like it. You state "Nobody is building an exceptional developer experience" and "There isn't a single developer-first email platform in the market today", and I have to disagree. Postmark has great developer experience. And the specific points you raise aren't much of a rebuttal:
- Templates: your own react.email project already has a Postmark integration. More generally, templating solutions don't need to be tied to the email service. I prefer to use separate libraries for rendering and then pass off the html output to the email service anyway.
- Slow performance: Postmark has excellent delivery speed.[1]
- Poor observability: Postmark (and every other service I've used) provides events.[2]
- Designed for marketers only: Postmark is clearly designed for developers, as are several other services.
I am rooting for you! But I'd also like to say that before you trash talk competitors, please be sure you have substance to back it up, because some of us actually like those competitors :).