I agree that Smalltalk isn’t suitable for all application domains, but neither are most other languages. Yes, Perl, Python, and Ruby are handy scripting languages, but C#, C++, Java, JavaScript, and PHP aren’t. (The latter two are very specific to the web.)
Other popular languages are also not for scripting: Groovy, MATLAB, R, Scala, Swift, and TypeScript.
The fact is, writing Unix tools is not a very large domain compared to web, mobile, data science, IoT, enterprise business computing, etc.
Nevertheless, Smalltalk is remarkably versatile. It can be used for just about everything I can think of!
The fact that it’s image-based isn’t really a handicap. Smalltalk can now integrate well with GitHub. And with GNU Smalltalk and Pharo (which now has a command line mode), you can even use it for scripting!
Like I said, there isn’t anything Python can do that Smalltalk can’t. The problem — the real problem — is that the programming community needs to be educated about Smalltalk. It’s a perception issue.