One very important reason. It's what I had in my garage. lolThere's an idea! When I did my fuel filter I spent an hour lying in salt water slush trying to free the rusted things. Is there any particular reason to use duct tape? I have some amazing self-vulcanizing silicone tape that would create a good seal.
The tape the factory used was something like a papery athletic tape. It tore off very easily (but stayed until I was ready to replace the filter). I'm not sure you need an incredible seal as much as you just want to prevent a ton of crap from building up all over/in it. That said, doing even better than the original tape isn't a bad idea. The thing I would avoid is introducing adhesive material into the quick disconnects, that's why I did the sticky side out layer first. The takeaway really is, anything is better than nothing. I had an absolute battle with the filter on my 07 XC70 because it was uncovered and filled with mud/sand/rocks/etc. I ended up having my indy deal with it.