Well, at least in part, it is because Land’s self-styled critics, such as, for instance, Alex Williams, write shit like this:
Where Deleuze and Guattari ultimately counseled caution, to accelerate with care to avoid total destruction, Land favored an absolute process of acceleration and deterritorialization, identifying capitalism as the ultimate agent of history. As Land puts it, “Capitalism has no external limit, it has consumed life and biological intelligence, [and it is] vast beyond human anticipation.” Here, the deregulation, privatization, and commodification of neoliberal capitalism will serve to destroy all stratification within society, generating in the process unheard of novelties. Politics and all morality, particularly of the leftist variety, are a blockage to this fundamental historical process. Land had a hypnotizing belief that capitalist speed alone could generate a global transition towards unparalleled technological singularity. In this visioning of capital, even the human itself can eventually be discarded as mere drag to an abstract planetary intelligence rapidly constructing itself from the bricolaged fragments of former civilizations. As Land has it, through the acceleration of global capitalism the human will be dissolved in a technological apotheosis, effectively experiencing a species-wide suicide as the ultimate stimulant head rush.
Marxists look at Land and they are scandalized by his writing; writings that violate their petty bourgeois sensibilities.