Capitalism requires a reserve army of labor to function.
This is typically expressed as the "natural rate of unemployment", which is formulated as some arbitrary threshhold - generally, although not always, around 3% - beyond which any further gains in employment will drive up inflation etc. as the much-increased ranks of the working-class demand higher wages. And this is necessary for less esoteric reasons - a reserve army of labor dissipates the organized power of unions, creates a mass which can be drafted either into the military or the productive economy during war or disaster, etc. Unemployment gives the capitalists 'flexibility'.
This is, to some degree, an actual recognition of class conflict: labor can never be too strong, or else they'll make demands of us we cannot possibly hope to meet. To a much greater degree however it is merely structural, and advantageous to capitals which exist to deal with the issues produced by the unemployed (temp services, State bureaucracies, the penal system, &etc.). Indeed, in a genuine full-employment economy it is no guarantee that interests lime agribusiness, which depend on programs like EBTT for regular infusions of profit, would not fail.
The Keynesian solution to this has been to turn the government into the employer of last resort. Which works -- for a time, until the private capitals necessary to fund the State are crowded out and exhausted by the entrance of the government into the field of competition. This largely accounts for the stagflation of the 1970s, incomprehensible to the bourgeois orthodoxy of Keynesianism.
Capitalism, in fact, has nothing against the lumpenproletariat as such; this is more a concern for the petit-bourgeois, themselves only ever a handful of steps from proletarianization. And being incapable of materially analyzing the society around them, this class turns to moralistic jeremaiads to explain endogenous occurrences within Capital, whether in defense of or in opposition to the lumpen.
