TIL directories still exist. Any other unknown ecommerce hacks?

Hello, while searching around today I came across a video that said a good way to build backlinks for ecommerce sites is to get on directories. I didn't really even know what they were or that web directories existed until then but it makes a lot of sense.

I'm wondering, are there any unknown/lesser-known off page SEO tactics like this one? Any is appreciated. Thanks.