Not our Jams specifically (thankfully), but it has happened in other popular Jams.
This measure is mostly a preventative one.
Try to imagine being in my shoes where some hacker could ask the same questions you are and then post a malicious executable and have a bunch of peeps get Malware/Ransomware and greatly inconvenient peeps.
There would be less trust in our Jams and therefore less turnout.
All it takes is one unfortunate incident to remove trust.