Help understanding a sentence extracted from The Economist

Question

His presidency will be counted in speeches because its trials proved harder to overcome than the barriers he scaled to attain it. Often he spoke as no other president could, becoming, through his identity and eloquence, a receptacle for the hopes of Americans and of—and for—the world. Think of his speech in Berlin in 2008, when he extolled multilateralism and the rule of law, or his now-defunct conciliation in Cairo the following year. Think of his eulogy after the Charleston killings. Yet posterity might score him higher on a broader metric had he been as effective in the more intimate persuasions of Congress, as consistent in projecting empathy as at exhortation, or more resolute abroad; had he been as adept at championing legislation or facing down tyrants as he could be at stirring hearts.

This paragraph is extracted from *The agony of hope 24th Dec. 2016 The Economist

This article is about Barack Obama, and my question is the parts in bold.

Is the sentence saying that "Often he spoke as no other president could, [and he was] becoming, through his identity and eloquence, a receptacle for the hopes of Americans and of—and for—the world.(a receptacle for the hopes of Americans and of the world and a receptacle for the hopes of Americans for the world)? Is it a good sentence?

Last question, the "at" in bold, isn't it suppose to be "in", since "as effective in sth as in sth"?

Thank you for your patience.

Answer 1

Playing with prepositions as the original does might be considered clever or clumsy—it depends on whether you take milk or lemon in your tea. It is a rhetorical flourish to package an idea in that manner.

... a receptacle for the hopes of Americans and of—and for—the world.

He became a receptacle for the hopes of Americans.

He became a receptacle for the hopes of the world.

He became a receptacle of hopes for the world.

Hopes of the world are the hopes of the people of the world. Hopes for the world are the wishes and desires for the future of the planet and all the nations and creatures on it.

BTW, although you can inject "[and he was]" before becoming as you have done, to make clear who the subject is, the participle clause that calls him a receptacle of hope does not refer to something done in addition to his speaking as he did; rather it refers to what happened by virtue of his speaking as he did, or concomitant with it.

The pilgrim walked up the steep hill, growing wearier with each step.

He spoke eloquently and, because of his identity, as no other president could, becoming a receptacle of hope.

P.S. The author engages in similar cleverness|clumsiness later in the passage, and loses track of the syntax.

...had he been as effective in the more intimate persuasions of Congress, as consistent in projecting empathy as at exhortation...

as consistent
  => in projecting empathy
as
  => at exhortation

The phrase "consistent at exhortation", which is not clever, is probably a residual effect of effective earlier in the sentence, which does license at. He was effective at exhortation. For the sake of syntactic parallelism, and for the sake of the argument being advanced, the author might have reordered things a little:

... had he been as effective in the more intimate persuasions of Congress as he was in exhortation, as adept at championing legislation as he was at projecting empathy, and as consistent in facing down tyrants as he was in stirring hearts.

But then, here, we're not writing to deadline. :)

Answer 2

Whilst there is nothing especially ungrammatical with the sentence, it is, in my view, unnecessarily convoluted, and the precise meaning is a little unclear.

I am confused as to whether it means, so far as "the world" is concerned, "the hopes of the world" or "the hopes of Americans for the world". Perhaps it is intended to mean both, and that maybe why such awkward syntax has been employed. Indeed I wonder whether the author would be able to explain what they did mean at this point.

Surely the import of the meaning could have been got across just as adequately by saying simply "becoming a receptacle for the hopes of Americans and the world".