Symmetric key crypto is a thing that exists.
Over the years there have been numerous popular symmetric-key algorithms like Twofish, Rijndael (aka AES), Salsa20, ChaCha20, Blowfish, DES, 3DES and more I'm sure - some of which are now known to be insecure (like RC4) - but Symmetric key crypto does work OK for bulk encryption for example.
Yes, they come with the drawback of needing a shared secret between two or more parties and you have thus to find a way to share the secret "secretly", but @kb1sph1 was upfront on this and said
So I'm not too sure why there is this debate here...
From what I see @kb1sph1 is familiar with other types of encryption and has made a choice... that was not the purpose of his question...