There are many proficient web developers who I'm sure could do a great job of whatever it is you are looking to build, and would be happy to build it to your specifications (like using Node for the backend).
I could be wrong, but I think it's likely that good independent web developers don't need to advertise because they probably already have full-time jobs or contract work via recruitment or word of mouth.
And I think that probably applies even more to good web dev agencies - they likely have enough work via word of mouth referrals and those little "Website made by Super Web Design" links in footers that they really don't need to advertise.
I have hired somebody on Reddit for a small job before (an illustration) and could not have been more impressed by the job they did. And I was really surprised by how little it cost, too - I'm not a wealthy person (currently a student) but I still paid them more than we had agreed on, because I felt like they deserved it.
What exactly are you looking to build? Could you perhaps put an email address in your bio and I could reach out and discuss it with you? I may not be experienced enough (although I'm familiar with Node) but I do have friends who are very proficient web developers (which is how I got into it). One of my close friends has been the CTO of multiple well-funded companies and I know he uses Node a lot.
This friend also developed a well-known web technology and somehow remains more humble about that achievement than I am about winning a spelling bee in 7th grade.
I don't believe he's currently looking for work (although I guess I could check) but he is a very friendly and generous person who is always willing to help people, and either he or I might be able to help point you in the right direction.
I guess what I'm saying is that if nobody else steps forward, I could be your ear in the business, if you're a reasonable person who would respect my time, which you do seem to be.
I have the feeling that you're right; there just isn't a market for it. The alternative would be to try and filter through the army of Fiverr, Upwork & Freelancer - but I fear the risk of spaghetti code or copypasta is high and there isn't much accountability on these platforms once the job is considered 'done'. Maybe I'm wrong though.