Why does it become easy for the political parties to ignore the reasonable demands raised by popular movements?

Both options, 1 and 2

Yet the real-life impact of these movements on the nature of public policies seems to be very limited. This is partly because most of the contemporary movements focus on a single issue and represent the interest of one section of society. Thus it becomes possible to ignore their reasonable demands. Democratic politics requires a broad alliance of various disadvantaged social groups. Such an alliance does not seem to be shaping under the leadership of these movements.