Blocking "all" filesharing sites? If your company is like mine, both federal regulators and clients regularly perform third party security audits. "How do you protect our data from exfiltration?" is a stock question. I've also seen "demonstrate you block viral vectors" lead to similarly unnecessary restrictions. Hell, I could see the above two answers explaining ALL of the symptoms your leadership has created.
It doesn't have to go that way, though. Leadership at my company had the same silly knee jerk reaction. I argued against it; but we did the same thing, for a while. About 15 months. It took 12 months for me to accumulate comparative data and about a month to polish it into a pretty presentation. It took another 2 months to cross fiscal quarters and then we immediately ripped all that none sense out and replaced it with a properly architected solution. We moved the critical data and all the workflow that touched it into secured remote VM's running on in house Virtual Desktop Infrastructure. All desktops/laptops are basically dumb terminals for accessing the work VMs. You VPN in to do that, regardless of where you come from - including our "internal" office vlans, which only have access to the internet and our VPN server.
Have work to do? Use your VM. Wanna fuck around on slashdot? Use your local machine.
Problem solved, and with MONUMENTALLY fewer man hours spent managing the ridiculously complex filtering mechanisms the previous authoritarianism had required.