From a third worldist perspective, many would argue that Trotskyists with the theory of “permanent/world revolution” put the cart before the horse so to speak, in that they do not accept the limitations of “building socialism in one country” and the reality of where many third world/global south/periphery countries start from, which is a rock bottom capitalist economy structured for exploitation by the imperial core/centre - see Micheal Parenti “not poor but over exploited” - and the contradictions that will occur because of this, when on a path towards socialism and dismantling this form of capitalism, contradictions such as stagism/two stage theory/new democracy.

In the countries of the (Global) South, most people are victims of the system, whereas in the (Global) North, the majority are its beneficiaries. Both know it perfectly well, although often they are either resigned to it (in the South) or welcome it (in the North). It is not by accident, then, that radical transformation of the system is not on the agenda in the North whereas the South is still the “zone of storms,” of continual revolts, some of which are potentially revolutionary. Consequently, actions by peoples from the South have been decisive in the transformation of the world.

Taking note of this fact allows us to contextualize class struggles in the North properly: they have been focused on economic demands that generally do not call the imperialist world order into question. For their part, revolts in the South, when they are radicalized, come up against the challenges of underdevelopment. Their “socialisms,” consequently, always include contradictions between initial intentions and the reality of what is possible…There is no “world revolution” on the agenda whose center of gravity would be found in the advanced centers. Lenin, Mao, Ho Chi Minh, and Castro understood that and accepted the challenge of “constructing socialism in one country.” Trotsky never understood that. The limits of what was achievable in these conditions, beginning with the heritage of the “backward” capitalism found in the peripheries, accounts for the later history of the twentieth century’s great revolutions, including their deviations and failures.

• Samir Amin, Revolution from North to South

I personally have no problem with Trotskyists as long as they are not overly sectarian or overly critical of states actually attempting to build socialism. It’s perfectly fine to have theoretical disagreements. As long as they’re still on the left, it’s all good.

Can’t speak for other countries, but in China we had very bad experiences with the Trotskyists (Chen Duxiu faction). The Stalinist/Comintern faction (Wang Ming) was also problematic, and Mao gave Stalin a 70/30 assessment, but with the Trotskyists, he completely trashed it. (There is a reason why Mao is so revered in China, for he succeeded in synthesizing the correct path for Chinese socialism, which could have easily ended in disaster had it gone down either of the other two paths)

The Chinese Trotskyists condemned any sort of collaboration with the KMT nationalists when Japan was literally invading at the doorsteps. For them, it is better for China to be colonized by Japan if that meant it could arouse workers solidarity across all the countries that are being colonized by the imperialists.

Trotskyists believe that international workers solidarity is the most important part of socialism, and strictly condemn any sort of collaboration with right wing nationalists, even when the country is under threat of fascist invasion. Mao wrote scathing remarks regarding such views in his essay on the role of communists in national wars, arguing that nationalism (in the third world sense, not in the European national chauvinist sense) is an integral part of internationalism and you cannot have internationalism without nationalism.

Note: to be fair to Chen Duxiu, he did eventually come to correctly identify the nationalist struggle as the principal contradiction for China at the time, and did renounce Trotskyism, but his tainted reputation would not be restored until the 1990s.