The above comment only applies to fake "leftism" and social-democratic reformist class-compromising politics. Since it misses all talk of socialist revolution, it could be construed as defeatist nonsense aimed at telling workers that "because of capitalism's globalisation and power" national overturns of the capitalist ruling class are impossible.
This doesn't reflect reality, and it isn't Lenin's view either. Instead, because of uneven political and economic development, it is co-ordinating revolutions in several countries at once, let alone say the whole EU, that is impossible.
There is also, of course, the notoriously clever-dick Trotskyist view that "socialism is one country is impossible" which is used to justify the Trots' poisonous hostility to the achievements of the Soviet Union and the Eastern European workers states (and which means these fake "left-wingers" never get outside of that Cold War anti-communist hostility to understand what really went wrong with the revisionist leaderships of these countries - and the insane Gorbachev liquidation of socialism).
As Lenin said in 1915, writing against Trotsky's slogan "For a United Sates of Europe": "[this is incorrect] because it may be wrongly interpreted to mean that the victory of socialism in a single country is impossible, and it may also create misconceptions as to the relations of such a country to the others.
“Uneven economic and political development is an absolute law of capitalism. Hence the victory of socialism is possible first in several or even in one capitalist country alone. After expropriating the capitalists and organising their own socialist production, the victorious proletariat of that country will arise against the rest of the world, the capitalist world, attracting to its cause the oppressed classes of other countries, stirring uprisings in those countries against the capitalists, and in case of need using even armed force against the exploiting classes and their states…
“The abolition of classes is impossible without a dictatorship of the oppressed classes, of the proletariat. A free union of nations in socialism is impossible without a more or less prolonged and stubborn struggle of the socialist republics against the backward [meaning imperialist] states.”
Outside of socialist revolution, the arguments against Keynes and "reflationary anti-austerity, anti-slump" economics are correct - monopoly-capitalism is deep in international crisis and warmongering across the Middle East and elsewhere - heading towards a third world war - and the global banks will bankrupt any country that seriously attempts to reflate. The trade war is being intensified and the 'left''s support for "economic nationalism" and "import controls" divides worker from worker and will eventually see world trade drop - greasing the slope towards world war.
So movements like Podemos in Spain and Syriza in Greece are indeed useless - and get nowhere - even when they are in government! The same applies to 'left' Democrat Bernie Sanders in the USA (who stands for import controls) and 'left' Labour leader Jeremy Corbyn in the UK, with his tepid "anti-austerity" proposals. They are just a gross deception of the masses.
Even Venezuela's half-way house Bolivarian revolution - the epitomy of left-nationalism in government that has failed to expropriate the local bourgeoisie and failed to go all-out to arm the workers to make the country a proletarian dictatorship - is struggling with violent counter-revolution, especially now oil money doesn't keep things going economically at a better level. Its leadership should rethink its non-Leninist attitudes, because it risks the kind of CIA-promoted coup that overthrew the elected "Marxist" Allende in Chile in 1973, which saw thousands massacred.
The highlighted article above says: "...demands to nationalize or collectivize the commanding heights of finance would not bring forth the egalitarian world they aim at. Rather, they would more likely accelerate current trends toward world economic breakdown and geopolitical belligerence."
But world economic breakdown and belligerence stem from capitalist crisis. The only way out of worsening "over-production" crisis and world war is the socialist revolution.
That has been badly hampered by the Soviet Union's ideological collapse in 1989-91 after decades of the Moscow leadership's retreats from Leninism and from decades of anti-communist Cold War lunacy (helped by the Trots' Orwellian view of the bogus "workers uprisings" in Hungary 1956 and Czechoslovakia 1968, etc).
But look at the Third World's growing rebellion against the Nazi-bullying of US and Western imperialism - what the sick fraudulent "democratic" countries call "terrorism".
Class compromise politics including the 'left nationalist' fraud do need to die. Revolutionary movements need to be built.
As and when Greece or Spain or the UK or India makes a socialist revolution they would not have to stand alone for long. A new tone would be set in world affairs. The ideological logjam would be broken.
Even before then, the appearance on the scene of any sizeable truly Leninist revolutionary movement would have a galvanizing effect on the planet.
Movements like Black Lives Matter in the USA and the surge of proletarian anger over the Grenfell Tower fire in the UK show that developments towards a renewed revolutionary workers movement are coming. Leninism needs to be rebuilt. See epsr.org.uk