I think this is quite a strange argument. Any technical show-and-tell in the form of 'I wrote a cool implementation of such-and-such algorithm' is obviously much less impressive if someone/something else wrote it, but that's always been true, and I think the Show HN format is largely used for tools or products that someone has created, in which case what's more interesting is the problem it solves and how it solves it. It's exactly as you say with your hypothetical biochemist; they've been looking for a tool like this! I don't think they spent much time worrying about how it was written or what the REST API would look like.
There is a proliferation of frameworks and libraries supplying all kinds of mundane needs that developers have; is it wrong for people Showing HN to use those? Do libraries and frameworks not lower the barrier to entry? There have been many cases of 'I threw this together over a weekend using XYZ and ABC', haven't there? What's interesting is how they understand the domain and how they address the problems posed by it - isn't it? Sure, the technical discussion can be interesting too but unless some deep technical problem is being solved, I don't care too much if they used Django or Flask, and which database backend they chose, unless these things have a significant impact on the problem space.
> the barrier of entry has been completely obliterated
I was very interested in 3D graphics programming back in the DOS days before GPUs were a commodity, and at that time I felt the same about hardware accelerated rendering - if no-one needs to think about rasterisation and clever optimisation algorithms, and it's easy to build a 3D engine, I thought, then everyone and their dog will make a game and we'll drown in crappy generic-looking rubbish. Turns out that lowering barriers to entry doesn't magically make everything easier, but does allow a lot more people to express their creativity who otherwise would lack the knowledge and time to do so. That's a good thing! Pre-made engines like Godot remove an absolute ton of the work that goes into making a game, and are a great benefit to the one-man-bands and time-strapped would-be game designers out there whose ideas would otherwise die in the dark.