Hi Chris--I completely agree that an engineer's ability to learn is a huge part of their value. With that said, many companies are searching for engineers who are intimately familiar with particular languages or frameworks. Anyone can get comfortable with a new framework over a weekend--it takes much longer to be become an expert.
Your idea for a better Glassdoor is an interesting. In the future we're hoping to build a set of tools for engineers who are interested in getting a job--we'd like to cater to both sides of the market.
Alex and I do not want to increase the volume of recruiting spam in the world. Poorly-constructed, boilerplate emails are the mark of a bad technical recruiter--we're not building tools to help them. We want to give the great technical recruiters a tool to help them figure out if they should be sending an email to an engineer in the first place. Furthermore, we're encouraging our customers to have the C*O's and engineers construct and send the initial emails--an email from the person you'd be working with is much better than another piece of recruiting spam.
If you'd like to get in touch and chat more please feel to email on richard@sourcing.io.