Yet the situation in Israel is very different from the situation in South Africa. Israel, unlike SA, has a broad Jewish working class whose interests are opposed to those of the ruling elite and to the occupation. The BDS campaign aims to boycott them too, thus making them fall easily into the hands of the bourgeois propaganda which claims that "the whole world is against us" and that "we must stick together as a nation". In effect, it harms the class struggle in Palestine by further segregating the Jewish and Arab proletariat instead of uniting them in a single struggle.
BDS replaces mass popular struggle with a plea to the capitalists and imperialists -- the international corporations and the bourgeois states -- to end the occupation themselves. It's hard for me to see how pleading imperialism to act in a certain way, instead of fighting it directly through mass struggle, is a socialist tactic.
Furthermore, BDS is also extremely hypocritical: its organizers would never call, in this day and time, for boycotts, divestment and sanctions on other "criminal" states, whose crimes far outweigh those of Israel. This is a second reason why BDS causes the Jewish proletariat to (rightly) think that it is being singled out and fall for the bourgeois calls for "national unity".
Regarding previous boycotts, note that their effect was completely negligible in comparison to the popular Palestinian uprisings.