Benefits of Observable with Http in Angular

From here: https://stackoverflow.com/a/40135509/462608

First this answer describes how Observables are helpful in preventing same repeated requests to the server and how we can pause between many requests so that the server doesn't get overloaded.

They it says:

As far as I am using Http in Angular, I agree that in the normal use cases there is not much difference when using Observable over Promise. None of the advantages are really relevant here in practice. Hope I can see some advanced use case in the future :)

What I understand here is that when Http is used then Observables benefits are not really relevant.

Why is that so? What role is played by Http in this case?
What topic do I have to study to understand Http's role here?

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