Is weak global economy always a "headwind"? In the most recent (Mar. 20, 2019) FOMC Press conference, Powell said this:


  So, global economy was a tailwind for the United States
  in 2017.  That was the year of synchronized global growth, and we
  began 2018 expecting and hoping for  more of the same. What happened
  instead is that the global economy started to gradually slow,  and now
  we see a situation where the European economy has slowed substantially
  and so has the  Chinese economy, although the European economy more.
  And just as strong global growth was a  tailwind, weaker global growth
  can be a headwind to our economy.


Question

His logic makes sense, and yes this is a world of interconnected financial markets, but I still wonder is Powell's assertion axiomatic here with the larger community of economists? 

Just merely playing devil's advocate, I would suspect that because of the Eurozone troubles in recent years, this helped the dollar stay stronger than it would have otherwise, citaris paribus. Not to say that currency valuation is everything, but is there really no counter argument for Powell's stance?
Randomly, I came across a compelling counter-argument just today which I will share below. I'm not sure I buy into this theory whole-heartedly, but there are some valid points and it's worth reading through, even just for the sake of generating more discussion:


  America benefits when everybody is worried about problems abroad, and
  as a result of that they buy dollars. What does that do for America?
  Well, a stronger dollar keeps a lid on consumer prices for Americans
  and it keeps a lid on interest rates for Americans. Also if people are
  buying into dollars and dollar denominated assets, it helps sustain
  asset prices. That's a double win; the worse things get abroad the
  better things get in the United States. But it works the same way in
  reverse. When people have a more optimistic outlook on global growth,
  then they don't need the dollar as a safe haven. And now the dollar
  starts to fall. That means we now have upward pressure on consumer
  prices. That puts upward pressure on US interest rates. And that puts
  downward pressure on US assets, because there is no longer demand for
  US treasury bonds, for US stocks, for US real estate, because now
  people want to invest internationally. That's where the money will go
  because that's where investors will find growth, and that will in turn
  hurt the US economy. -- Peter Schiff