OK, so you have written such scripts to notify you. Now the company decides they do not need you any more. Are you going to rewrite those scripts to notify someone else? Or even bother to mention to someone that they should do so?
Or the other scenario where you get another job midway between renewals (when you have not had a notification in several months). Will you remember to change who gets notified? Will you remember to tell someone? When you remember 3-6 months later that you would be getting notifications about now, will you call your old employer to let someone know the notifications were never changed?
In a lot of companies, certificate renewal becomes someone's job because they are in the right place at the right time to handle it and everyone else forgets that it even happens until something goes wrong. If nothing goes wrong for several years, no one, except the guy who handles it, remembers that it even happens. This happens with a lot of tasks, and is my biggest fear whenever someone leaves our IT Department: what minor tasks were they doing that they were doing so well we all forgot about them?
It has been great at my current job, only one of the people in our IT Department who was here long enough to do anything everyone would forget about who subsequently left was good enough at it for people to forget...that one person only left because they became suddenly ill and died. Dealing with their absence has been a mess.