See https://youtu.be/GCVJsz7EODA and https://youtu.be/V82lHNsSPww
There are a few problems, but I believe the biggest issue is that .zip and .mov are valid and common file extensions, and it's common for people to write something like 'example dot zip' or 'attachment dot mov' in emails, tweets, etc. Things like email clients have features where they automatically convert text that looks like a web address into clickable links. So now, retroactively, all those emails etc suddenly have a link, where they used to just have text, and the domains that are equivalent to those previously benign file names are being purchased by nefarious actors to exploit people unaware of the issue.