Most recruiters view a LinkedIn profile as an invite to reach out to almost anyone, and many recruiters apparently are reaching out to people who explicitly say

Most recruiters view a LinkedIn profile as an invite to reach out to almost anyone, and many recruiters apparently are reaching out to people who explicitly say "please, don't contact me if you're a recruiter". There used to be an "interested in" section at the bottom of profiles. It appears to be gone now, and you could check off things like "Career opportunities", "networking", etc. That section appears to be gone now. Using LinkedIn isn't lazy for recruiters, it's smart - it's just the easiest way to find people. The easiest way to find active job seekers would be resume/job boards. Recruiters who limit themselves to only using LinkedIn to identify potential candidates are lazy. Many devs could be found in a host of other places, and many like you don't want to be on LinkedIn. The other reason recruiters tend to rely on LinkedIn is they can get quite a bit of value out of it even at the free level.