it wasnt banned, it just wasnt allowed to be advertised and was only allowed to be sold in 18+ stores or closed off 18+ sections. it didnt have an official release but the german version could still be imported from austria for example
I always find this line of thought and odd one in discussions of German censorship.
So a government mandated/backed body, with government agents formally sitting on the advisory body/decision making body, acting with full force of law, sought to heavily restrict the sale (do/did many game shops have said gated off area? I am actually curious there and would love to see pictures), and marketing* of a work. In the absolute technical sense I suppose it was not a ban. For the purposes of colloquial discussion though then hard to argue otherwise.
That there seems to be little factual/rational basis for it either, and how countries of similar history, genetics, culture... fared just fine is just icing on the cake.
*marketing as a percentage cost of development is considerable, and if films are any example (and films and games have broadly the same audience, budget at least these days, technical skills flowing both ways, share artistic concepts...) might even be more than the actual development aspect. If companies did not think it worked, and we also have examples of badly marketed games before (see many a hidden gem, and a lot of stuff in the late 360 era from Japanese companies outside Japan), then they would not pay it for I am sure we have also seen how penny pinching they are in all other aspects, often by necessity (how many game companies make it to their third game or ten years with a general growth trend?)