The post already explains in painstaking detail why network effect requires us to adopt extreme measures (which you mischaracterize as “you’re either with us or against us”). It’s the nature of the conflict, and free software advocates must either recognize it, or continue to suffer the dominance of proprietary software.
The issues with Matrix are perhaps better explained by others, elsewhere.
Fossify File Manager (formerly Simple File Manager) has this functionality. I haven’t tried it with networked drives, though.