There's a lot of you out there, all with the same aims and often, fronting the same positions.
LinkedIn is a social network for careers, career building, switching jobs, showcasing yourself online, etc. Anyone with a profile should be prepared to receive a lot of Inmail. I would posit that it's a decent measure of how strong your profile is.
At any one time, a prospective candidate's profile isn't likely to say "I am looking for work" in big bold text. Generally, this will be for two reasons. One; existing colleagues are likely to be connections. Two; once one declares one's availability, one's value decreases.
This makes it very difficult for recruiters to target those who are actually open to being contacted. I don't see a way around this.
The other problem with attempting to target is that keyword based skills matching doesn't work within the recruitment subcategory of developers. If I know Yii, Laravel and Zend I could pick up Symfony very quickly, but that doesn't come across from a CV scan. Maybe the ideal candidate for your role is someone looking to learn a completely new programming language for their next role? Primitive keyword matching makes it even harder for recruiters to find the right people. What it does do instead, for those who are aware of it, is widen the circle of potential candidates, making the whole situation far worse.
Blanket vs Target
The two primary strategies for approaching someone. As discussed already, targeting is seriously difficult, if not impossible. So, as a recruiter, you are left with every single developer on the network within a commutable radius of the position left to contact.
Let me just pause for a moment. Some of you don't even bother to narrow the search based on location. I am curious as to whether this is oversight, foolishness or something clever that I am missing? My personal favourite was a request a few months ago, suggesting I might like to escape the hustle and bustle of the big city and move to Exeter. In a game where you must play the percentages, isn't that approach a complete waste of time and resources?
As we are left with the only option to blanket contact everyone in sight, it becomes not about the candidate but about the recruiter.
Developers receive numerous messages, from different recruiters, who inevitably are recruiting for the same few jobs each month or two. At this point, you the recruiter must stand out.
The hypothesis is as follows: as a recruiter, I will achieve a higher percentage of candidates accepting my connection request if I put a bit of time and effort into it and come up with something unique.
Please note that this is a hypothesis and by definition requires testing. It may turn out that it's false, in which case feel free to continue as you are.