It is important to remember that there are scanners running over all IP addresses on the internet and checking for all the new vulnerabilities. So if you are not updating your services and one of your services has a vulnerability that already has an open source module to scan for it, then you are going to get scanned and you are going to get exploited. So it’s not just about having basic protection, it’s also about being really up to date, which not everyone is doing properly.
The door is the warmest part of the fridge and I would guess this has something to do with the temperature of an average fridge being a bit too cold and producing a less favorable texture so the manufacturer wants you to have the best experience and tells you to put it on the door. Either that or something else probably related to you enjoying it more or using it more.