It really doesn’t because hair typing isn’t real. Density and porosity are real but the idea of 3c, 4c just simply doesn’t exist in a science context and it’s more of a marketing ploy these days. That’s not to say there isn’t a difference in curl patterns but the system is just simply made up.

I have 3c and I use “white people shampoo” because it just works and it’s cheap and it comes in a big bottle. People associate traits with certain hair types that leads them astray to an extent. Like when people with 4c hair find out they have very thin hair and it’s surprising because it’s thought to be super rough and coarse and thick. Likewise, there’s people with looser textures who think they have fine hair but they have actually coarse hair but they think it’s fine because of the curl pattern.

Anyways, this is all long but in summary, no you are not confined to certain shampoos because if your hair type. You may get more benefit for stuff geared towards your hair type but I think people have better success when they just use what works instead of using what it’s marketed as