I don't know the exact history of OTel, but I agree with you. A few years ago, open source applications basically included one type of telemetry: Prometheus me

I don't know the exact history of OTel, but I agree with you. A few years ago, open source applications basically included one type of telemetry: Prometheus metrics. (Maybe Jaeger for tracing if you're really, really lucky.) What OTel is is a way to write an open-source library that emits telemetry, but without dictating that the end user use a particular storage system. Basically, you can use Datadog instead of the open-source stuff, even if the library authors have never heard of Datadog. Datadog specifically, I don't know if they care. They had an army of junior engineers that existed to hack Datadog into every open source project imaginable. If something had monitoring, they would just add their vendor-specific stuff and upstream it. That was probably expensive but probably accounts for a vast amount of their early marketshare. The other vendors wanted in on that racket without having to do too much work; OTel was born.