But they did not achieve widespread adoption.That's always the issue with small, clean implementations. They work when they only apply to one domain.
Sorry, but this is pure BS with regards to Smalltalk. I worked for a Smalltalk vendor for 5 years, then consulted in the language for several years after that. I had a front row seat to these issues. Having a small language does not make it suitable for only one domain. The primary reason for Smalltalk not achieving widespread adoption was due to a series of decisions which, in retrospect, were highly anti-adoption. It started with no operator precedence in the language design, which acted to alienate engineers and scientists. Then the industry went through a "we're the boutique language of the Fortune 500" phase with $5000 and $10000 per-seat licenses.
It is no different for software, blenders, bicycles etc. Once something is used for multiple domains, it now needs to become larger and more complex. Its basically a rule of nature.
That just doesn't work for software. The reason why Python is so popular with certain scientific communities isn't at all specific language features to support them. It's general utility plus specific libraries. The reason why Smalltalk got popular at one time in finance and energy trading didn't have anything to do with specific language features or libraries. It was purely rapid development!
There is something which a small language can be prone to: fragmentation. It was so easy to roll your own Smalltalk. This, combined with a toothless language standard meant that the community got balkanized into multiple communities with incompatible code.