Note that these products aren't the same, even though they all fall under the category of observability - similarly to how you'd use Datadog AND Sentry, although both can be called "observability platforms".
I do think vendor locking is a key differentiator, which some of the reasons why OpenTelemetry succeeded in the first place. I know that my previous company switched to OpenTelemetry for exactly this reason. You get the flexibility of using any platform you'd want (since we're compatible with OpenTelemetry), so it's not vendor-locking you to a specific platform with specific capabilities. Why use any of the ones you mention - maybe Datadog is enough if your use case is simple?
But there are more advantages - you get much more than just observability to the LLM itself - you can see calls to vector DBs, network calls, DB queries, etc. - this can be extremely useful IMO for RAG and autonomous agents for example
I do think vendor locking is a key differentiator, which some of the reasons why OpenTelemetry succeeded in the first place. I know that my previous company switched to OpenTelemetry for exactly this reason. You get the flexibility of using any platform you'd want (since we're compatible with OpenTelemetry), so it's not vendor-locking you to a specific platform with specific capabilities. Why use any of the ones you mention - maybe Datadog is enough if your use case is simple?
But there are more advantages - you get much more than just observability to the LLM itself - you can see calls to vector DBs, network calls, DB queries, etc. - this can be extremely useful IMO for RAG and autonomous agents for example