Neither Europe nor any North and South American country with the single exception the US boycotted Cuba, so the boycott argument is simply putting wool over the eyes. I would add that Chilean ag products did face consumer boycott after Pinochet, not just in Europe but in the US, so the comparison is fair even by your own standards.
I am not denying the successes of the socialist economy, but that does not mean that I have to deny the existence of the problems. The crux of the problem, in Cuba and elsewhere, is the large segment of the population working in the subsistence (or inefficient) agriculture - which is one of the key causes of poverty and underdevelopment. The socialist economies developed a rather good solution to that problem, that had very little social cost - much lover than transition cost in capitalist economies - but it could only go so far. I would venture to say that it was easier to reduce ag employment from, say 70% to 30% then from 30 % to 15%, mainly because 30% ag employment usually means the presence of a fairly well established industry and service sector for which the transformation measures used in the past do not work very well.
Wojtek