Dead wrong on Git, not to mention the general, inherent issues with locking your ability to freely share your data behind the monthly plans of cloud vendors. No, local sync isn't a replacement as it's often in a non-free binary format. Cross vendor compatibility issues are waved away as "having to work a little harder". Rarely has a sentence done so much work.

The author attempts to moderate at the end by saying sometimes you need a local copy. However, as this option becomes rarer, so do the tools that support it. Eventually, you won't even get to make that choice.

As for development, "merging" is far more complicated than for text documents and cannot be left to an automated system.

Is sharing files less secure? Surely. Is it worth it? Yes.