The qualitative difference is that today it is trivial for a "knowledge worker" (which includes a software developer) to control his or her own means of product

The qualitative difference is that today it is trivial for a "knowledge worker" (which includes a software developer) to control his or her own means of production (basically a laptop and an internet connection). In Marx' time, the means of production was a factory or large areas of arable land, and those weren't, and generally still aren't, possible for individual workers to own. This situation gave the owners of those means (capitalists) undue negotiating power over the workers -- hence collective ownership of the means of production by the owners. In the first paragraph, I'm purposefully steering clear of the word "own" since there are grey areas, what with binary driver blobs on the computer, and especially the fact that you never meaningfully "own" your internet connection and many of the services you rely on. Yet I would argue that this is a very (quantitatively) different situation from the worker/capitalist class struggle of Marx' time.