I skimmed it and didn't see it compare effective tax rates. This article is very useful analysis but it misses a large part of the context once you start talking about actual amounts paid in taxes
US tax system has very few loopholes. Double Irish / Dutch sandwich avoid EU taxes, not US. US tax on foreign income can be deferred - indefinitely - as it is only paid when the money is repatriated. But to truly avoid US corp tax is generally pretty limited (leasing IP from a foreign company etc).
For example: If US company X makes $100B in foreign income in 2017 and repatriates that income in 2019, they will book 0% tax paid in 2017.
Similarly, if X pays income tax to a foreign government they will receive credits for tax already paid - but due to accounting practices the US government will not count the credits when publishing the effective tax rate of X. That last point isn't germane to this particular article but it is something behind many of the 'Look at the low tax rate of X' articles you will see around.
As a proportion of GDP the US was already lower than average.
https://www.npr.org/2017/08/07/541797699/fact-check-does-the...
I don't know enough to argue for one side or the other, but I think the provided link could be misleading (not necessarily intentionally)