Selfhosted

One related story: I did have the arguable pleasure to operate a stateful Websockets/HTTP2-heavy horizontally scaled "microservice" API with Rails and even more Ruby, as well as gRPC written in other stuff. Pinning of instances based on auth headers and sessions, weighting based on subpaths, stuff like that. It was originally deployed with Traefik. When it went from "beta" stage to having to handle heavier traffic consistently and reliably on the public internet, Traefik did not cut it anymore and after a few rounds of evaluation we settled on HAProxy, which was never regretted IIRC. My friends company had it in front of one of the countries busiest online services at the time, a pipeline largely built in PHP. Fronted with haproxy. I have seen similar patterns patterns play out at other times in other places.

Outside of $work I've had them all running side by side or layered (should consolidate some but ain't nobody got time for that) over 5+ years so I think I have a decent feel for their differences.

I'm not saying HAProxy is perfect, always the best pick, has the most features, or without tradeoffs. It does take a lot more upfront learning and tweaking to get what you need from it. But I can't square your claims with lived experience, especially when you specifically contrast it with Traefik, which I would say is easy to get started with, has popular first-class support for containers, and loved by small teams - but breaks at scale and when you hit more advanced use-cases.

Not that any of the things either of us have mentioned so far is releveant whatsoever for a budding homelabber asking how to do domain-based http routing.

I think you are just baiting now.