Did Buddhism fuck up Burma?

No. Buddhism is a perfectly okay religion and Lord Buddha even said some nice things about the Merchant class. The problem for the Burmese was that their language was so saturated with Buddhism that Communist ideas, translated into Burmese, became ethical or soteriological rather than historicist or strategic. For example, when Thakin Soe and Than Tun (Aung San's brother in law) wrote the first book on Marxism,  the term they used for the Marxist dialectic was 'anya-manya' which conveyed something like 'the system of phenomenal correlation' rather than anything involving evolution by means of sublation or synthesis.

Rapid advances in Burmese higher education, as well as dramatic changes in the World Order which projected young Leftists into positions of National leadership and Global standing, meant that Thakin Soe's conceptualization of Marxism soon ceased to be productive of creative thought.
Certainly, by the time of the military coup in 1962, the Junta's official ideology of anya manya Th'baw tra (System of Correlation between Man and his Environment (SCME) based on the work of a student of Thakin Soe, U Chit Hlaing) was considered neither Buddhist nor Marxist nor other than fuckwitted by most intellectuals.
However, the Burmese Communists obsession with purity of doctrine- in particular their bizarre insistence that to gain power save by revolutionary means was illegitimate and represented the heresy of 'Browderism'- had by no means disappeared in the 20 years following Aung San's assassination. Rather it had gained in virulence and led to violent purges of Party loyalists- including, the Bengali, Ghosal who had himself denounced Browder many years previously.

It is tempting to speculate that Burmese Buddhism lays greater stress on 'proper means' and this somehow forecloses 'multiple realizability' in a manner which explains the bloody and apparently quite pointless internecine problems of the Burmese Left.  The truth is less interesting and probably has to do with getting hold of guns and canon fodder.