You don't really know that, maybe you missed out on interesting jobs and you'll never know.
At the very least, receiving recruiter emails from LinkedIn allows me to do networking and meet a lot of influential people at various companies, even if I don't end up landing a job there. It also builds my recruiter network, which is never a bad thing: if I ever need a job one day, I am planning to spam my entire network of recruiter, let them know exactly what I'm looking for and let them do the work for me. It goes both ways.
I respect deciding to opt out of LinkedIn but there is an opportunity cost to such a decision that you seem to have overlooked.