Maybe the people that have SEO companies are bsers. Because really, if they were so good at that, they could make a lot more money easily building their own sites.
But SEO itself is not bs and is necessary if you want to rank anywhere where customers can find you for things that are not primarily related to your unique web site name.
My own experience is that links are very important for highly competitive keywords.
Good content and design is king for words/phrases related to highly competitive keywords.
It’s all manipulation but some forms are more embarrassing than others 