Except that your name is also put on your doorbell with a label-maker, so anyone in your apartment could easily find out which flat was yours. Furthermore, the downstairs/apartment building's set of doorbells also proclaims last names, and are often ordered by floor. E.g. I live on the third floor, and my doorbell is second highest.
In fact, it's advised that you don't put any first initials/first names on your doorbell, because then people could be inclined to send you prank takeaway food, for example, because they know your address and full name just by standing outside the building.
I've generally found that the order of the names on the doorbell list roughly matches your floor. So if you're on the 2nd floor, right side from the stairs, your doorbell is second from the bottom, on the right side.
Obviously, there's no standard nor convention, but Hausmeisters seem to find it convenient, and I like it when I can do that when visiting a friend for the first time.
Of course there are, however, apartments whose Haustür (the door to the apartment building) leads to several different buildings or staircases. In that case, good luck ever finding that person even if they want you to come visit.
In my city (Leipzig), all apartments have these. All the last names are listed on doorbells, and you have a phone in your flat, from which you can unlock the apartment building's front door without coming down.
So, in total, your name is three places in the apartment: at the entrance next to a doorbell (which effectively "calls" your flat), on your mailbox, and above the actual doorbell near your flat's front door.
I live in Leipzig and I have no name on the doorbell near my flat door. If they deliver a packet to a neihgbor I have to go out and ring the doorbell at the entrance, or guess which apartment it is :)
In fact, it's advised that you don't put any first initials/first names on your doorbell, because then people could be inclined to send you prank takeaway food, for example, because they know your address and full name just by standing outside the building.
So...this point doesn't make any sense.