Most recruiter contacts are low quality, but I reply politely anyway telling them exactly what would be a quality job for me. 90% of them never respond, but the other 10% do and their quality of communication increases. A few have even called me up and started open discussions about trying to match me to roles. 3 out of the 4 jobs I've had over the last 15 years were landed this way.
So yes, if you sign into linked in and then treat recruiters like a worthless enemy, you are using it wrong. If you respect them as people and help them to do their job better, it can work for you.
I'm not saying Linkedin does not have problems... it does. But your responses to it can help.
I have had success by actively cultivating a small number of recruiters I perceive as high quality.
I find them if they are offering roles that are truly unique and special I will reply back and just say "hey I am not in the market right now but lets have a chat, this sounds interesting.."
Unique and Special defined here as either high level jobs that typically aren't widely advertised, Director/VP/CTO type stuff, or even IC stuff with "above market" comp. I am not in the right half of that group yet, but its what I am eyeing in a few years. Jobs with under-the-radar firms doing some really interesting things- I used to work in HFT and prop trading, and there are dozens of very successful firms you haven't heard of that have a minimal website, if they have one at all- the only real way in is to know someone there, for them to find you, or these recruiting firms. There are usually tells in the job listing/pitch though that this might be one of those firms.
Sometimes they just make a decent pitch that shows they actually read my profile and seem to understand where my career arc is going so I will give them a reply. A very decent just basic filter though is seeing if they have been in the industry for at least 10 years. So many churn and burn through the industry and move on to something else. I have "grown" with several recruiters that now do mostly executive and very big comp roles.
These days this happens about twice a year at most, but keeping that "stable" around has been helpful. In the past I have kept the list and shot off an email saying "hey its time for a change" and its been very helpful, though my last three roles ended up being through recommendations from previous coworkers.
So yes, if you sign into linked in and then treat recruiters like a worthless enemy, you are using it wrong. If you respect them as people and help them to do their job better, it can work for you.
I'm not saying Linkedin does not have problems... it does. But your responses to it can help.