Coat-tail politics SUCK
Perhaps, but coalition politics are the ONLY way to win, short of being the oil industry and just going out and buying your politicians outright on the open market. Yeah, Harvey Milk won because of a huge amount of support from the gay community, but what really made the difference between the election he won, and the earlier ones he lost was not the gay vote, but the union support. Harvey worked very hard to win the support of the unions by supporting union causes (to this day it's all but impossible to find Coors in any SF gay bar). That's how it's done, and that's how its won.
they seem not to typically give a damn about whether it sinks the individual (as we just saw in recent litigation)...
Put the blame for that where it belongs (as you correctly did in an earlier post). It was her lawyers who CHOSE that route - ill-advised perhaps - and not the 'cause' that forced them too. She could have refused that defense by firing her legal team. But being opportunistic, she saw only the dollar signs and let that blind her to the writing on the wall which would have said that 'cause based' (just like 'gay panic') defenses rarely work.