Relying on recruiters.
Recruiters are notorious for buzzword searching and resume stacking. And Googler's probably don't respond to interview requests because they don't trust or respect recruiters (just a hunch).
Find other ways to advertise your jobs, like old fashoined networking, message boards, social media, etc.
"Must have 2 years of T-SQL." Ok, I've written my share of SQL for ASP.NET and desktop apps on MSSQL Server. Add it up and it's about 4 years, plus the last year or so with EF. Here's my resume.
"We can't send this to our client, you don't have T-SQL." Umm... SQL on MSSQL Server _is_ T-SQL. "Now you're lying to me." Ok, this is where our professional relationship ends. Thanks for your time.
Then there's that job where I pitched in on some Java stuff that needed doing. Similar to C#, I can grok. We got that code out the door, and it's still working. Yay. "Hello! I want to tell you about an opportunity requiring 10 years of J2EE and [insert other Java tech buzzwords]." <sigh> I'm not a Java guru anywhere near that level. Let me rewrite that project so Java isn't on there anymore. Doesn't matter. My resume is now in some resume bank that farms it out to non-perceiving headhunting companies.
Yeah, I'm getting a little cranky now. I'll stop.
I wouldn't have any trouble spinning up a product on that stack if I knew I could deploy it without spending a lot on just the software stack (especially if I was bootstrapped)
Their partner program action packs are relatively cheaper than buying the individual products ($429 Design and Dev action pack includes pretty much everything) or an MSDN subscription.
Their BizSpark program is aimed at keeping costs low during development and Azure has simplified deployment (1 shared instance + Sql Database + 50GB bandwidth for $25/mo).
I've found Node to be a good supplement for some middleware (but it still has bland RDBMS support especially with SQL Server).
I just tell "recruiters" that yeah "I know Java and .NET - expert in everything. Let's talk compensation..." and just wait till I talk to the actual tech lead to explain my skills and experience in detail. From what I noticed, if you have worked in one stack or the other you are experienced in my book, you can catch up on the details (WebAPI? Scala?) during your first week.
It might be worthwhile investing in a 9 or 12 week course to pick-up rails at Hackbright Academy, or one of the other programming intensives. Given your years and years of experience, I'm sure you'd have no trouble picking it up quickly.
I'm not dismissing your larger point that a good engineer can quickly take on a specific stack - engineering is what is important in a good employee, not knowledge of a specific API.
Define clear goals, values and process and then Hire someone to do it. Let them fill the funnel through boards, social media, recruiters or other marketplaces (cough Hired.com cough). You and your team can then evaluate and hire.