Does that mean that I and people like me cannot do open source in 2021? It means few people will hear about or discuss your projects, and that means you won't

Does that mean that I and people like me cannot do open source in 2021? It means few people will hear about or discuss your projects, and that means you won't get the critical mass of people necessary for your project to become popular. If you also conflate popularity with usefulness or importance then that's a problem. Pretty much all big open source projects have benefited from "marketing" of some sort or another. If you're unwilling to do that then you're limiting the scope and size of what you can accomplish to what you can do on your own. However, devs who are happy to contribute to an existing project where others do the social stuff are always welcome on pretty much every open source effort. So of course you can do it.