Because one big mistake many people make is writing down the name of the wallet that the seed phrase becomes to, and as such making it very easy for anybody to have access to your fund automatically. But if we can write just only the 11 Seed phrase without a clue which wallet it becomes to, it will be very hard for anyone to have access to it very quickly.
If the name of the wallet is just some gibberish then that information is not going to be helpful to anybody without having access to the device. Besides, it's most likely the case that the person has only one wallet on their computer anyway, so anybody searching the wallet folders on the device will only find just the one wallet.