> Do you have a concrete example of something you can do in a lisp repl like emacs that would be impossible to build into a python repl?
This is a challenging question, it's difficult to answer in a short few sentences. One practical example that immediately comes to mind is the advising system of Emacs, where you can modify specific parts of any given function, which isn't easily achievable with Python.
In a Lisp REPL, you can modify the behavior of the REPL itself on the fly, e.g. advising it to print the execution time of each expression sent to the REPL. The homoiconic nature of Lisp allows us to treat the REPL's evaluation function as data, modify it, and immediately see the results. This level of runtime modification of language constructs is not possible in Python's REPL.
You can get very specific and start challenging that statement. We can talk about bytecode execution, and how you'd need to modify the bytecode at runtime or alter the interpreter's execution loop, or Python's function object structure, or method resolution order. We can talk about descriptor protocol which handles method binding, we can speculate about JIT complications, thread safety, garbage collection, etc. At the end, it all boils down to homoiconicity. The homoiconic nature of Lisp - Code As Data, Uniform representation, Meta-circular Evaluator, etc., all that makes the difference for the things that aren't realistically achievable in non-Lisp languages.
That opens up many interesting practical possibilities, like creating interesting DSLs with minimal syntactic overhead and runtime efficiency.
People love their favorite programming languages for their specific features. They get used to them, it's a matter of familiarity, they get attached to their language of choice. Almost every language book offers you some unprecedented magic with their language.
And often programmers look at Lisp as just another programming language, missing the main point about Lisp, which is not one concrete language implementation but the idea as a whole.
Learning Lisp offers something fundamentally different. It's not just about acquiring a new syntax or set of features, but about gaining a new perspective on programming itself. Lisp provides insights into the nature of code and computation that are hard to fully grasp in other languages. The benefit of learning Lisp isn't necessarily in using it for every project, but in how it reshapes your thinking about programming. It can make you a better programmer in any language by deepening your understanding of abstraction, metaprogramming, and the relationship between code and data. Many concepts that originated in Lisp have influenced modern languages. Understanding Lisp can help you appreciate and more effectively use features in other languages that were inspired by Lisp, and that is a pretty much every PL in the TIOBE list.