> what is stopping it from being more widely adopted.
The best tools usually need a level of skill or patience that most developers just don't have time for. And companies have to ship with the developers they actually have, not ideal ones.
Lisp, formal methods, immutability, property-based testing - we agree on these. They just demand more than most people can give under a real deadline. A tool that shines in expert hands but falls flat for everyone else will lose to a tool that's just okay for everybody. Every time. That's basically what "worse is better" means.
In our industry we tend to approach things with "scientific methods", without actually using scientific methodology. Nobody experiments developing a real business solution with multiple teams using completely different set of tools just to see which one proves to have better ROI. What we do instead is that we go to forums and emotionally "mansplain" our anecdotal, subjective feelings about a tool or technique. Anecdotes aren't completely worthless; they're low-quality evidence, which is different. A senior engineer saying "every time I've seen a team adopt microservices before they had the operational maturity, it ended badly" is transmitting pattern-recognition from, say, fifteen projects. That's not a randomized controlled trial, but it's also not nothing. But there's flood of "unfalsifiable anecdotes" - claims structured so that any counterexample gets explained away ("you weren't doing real TDD...").
Rich Hickey's talks are not science - they're argument from principles, with illustrative examples. But they're honest about being that. He doesn't pretend to have benchmarks proving immutability is better; he reasons about it from costs and trade-offs and lets you decide. That's a legitimate mode of technical discourse. Contrast with someone claiming "studies show" functional programming reduces defects by 40%, citing one paper with n=12 undergraduates. The second is worse, and it's worse specifically because it's pretending to be scientific while the first isn't. I think the solution is not to make the field more rigorous and more scientific and require solid peer-reviewing of every idea. It's making the field more honest about the kind of claims we make.
Clojure remains hard sell to beginners because they haven't suffered enough yet. Experienced engineers get excited about immutable data because they've spent nights debugging race conditions. They appreciate simple functions-and-data because they've been lost in a tangled class hierarchy. The language solves problems they've actually had. Junior devs haven't hit those walls yet, so the solutions feel pointless. Why would you care about a painkiller if nothing hurts?