I mostly program with clojure. I'd love that I could agree with you. For clarity I was not meaning a culture of improductivity (but it also applies), and more of a trait of the culture that is improductive, choosing to focus productivity on the wrong goals, such as reinventing everything to do it "better", "more data-driven", "decomplected", etc.
> You can take it word-by-word and apply to say Javascript, and it would largely feel true - JS arguably has the worst fragmentation of any ecosystem; dozens of competing frameworks, build tools, bundlers, test runners; new frameworks constantly replacing old ones; "Javascript fatigue" is a real thing, etc., but nobody talks about "Curse of Javascript"
You also need to take into account the denominator of "number of users", though. Clojure, with a tiny population, had a cambric explosion of libraries, and now we can't argue that those are dead on one argument, and that those are "done" on the next one. There is a huge fragmentation in the clojure world, and on small populations, that hurts. Case in point: SQL libraries. Korma, yesql, hugsql, honeysql, and those are just the popular ones. Case in point: spec vs. schema vs. malli. Case in point: leiningen vs. boot vs. deps.
> I learned Lisp (once) and that opened up path to Clojure, Clojurescript, then Fennel, Janet and Clojure-Dart, libpython-clj, there's Jank that is about to break loose.
As we lispers like to say a lot, the syntax (or lack thereof) is the smallest of the issues. There is a lot of semantic difference between all of those (except libpython-clj, which does not belong to that list; but we could add Hy instead). That's even before starting to talk about library compatibility. So I'd contest whether having a common syntax is a major productivity gain.
I think you're confusing newcomers landscape of "which library do I pick", (which is real) with stretched evidence for fundamentally fragmented ecosystem.
Let's walk through your examples:
SQL libraries: Korma is dead, YeSQL is dead, HugSQL is in maintenance mode. The community converged on next.jdbc + HoneySQL. That's not fragmentation - that's exploration followed by selection.
Build tools: Boot had its moment, it's essentially gone. Leiningen is still around but new projects overwhelmingly use deps.edn. That's not fragmentation either - it's a transition, and a remarkably clean one.
Spec vs. Schema vs. Malli is the most interesting case because the convergence is still in progress. Schema is effectively in maintenance mode. Spec has stalled (spec2 never really shipped). Malli is clearly gaining momentum as the community choice for new work, largely because it treats schemas as data — which is very Clojure. But even here, these aren't competing implementations of the same thing the way, say, Javascript build tools are. They have meaningfully different design philosophies, and the community is converging on the one that best fits Clojure's values.
Compare it to JS, where we have Webpack, Vite, esbuild, Parcel, Rollup, Turbopack, and the "winner" changes every 18 months. Or Python's packaging story - pip, pipenv, poetry, conda, PDM, uv - which is still a mess after decades with a vastly larger community. Fragmentation in large ecosystems often doesn't self-correct because there's enough mass to sustain competing approaches indefinitely.
The small community size that you frame as a weakness is actually why the self-correction works. There aren't enough people to sustain five competing SQL libraries, so the best one wins and everyone moves on. The tight community, the shared values around simplicity and data orientation, and the fact that people actually talk to each other - these create selection pressure that larger, more diffuse ecosystems lack.
The productivity gains aren't speculatory - from the most pragmatic angles, I see time and again - they are real and palpable.