That’s not a matter of the language; and I don’t mean that in the “No True Scotsman” way either.

Lisp definitely allows you to write code that is very easy to come back to and understand. I’ve written code like that, and I’ve seen code like that in eg certain sections of the SBCL internals, among many other projects.

However, there’s a reason we don’t write all our code in Python or Assembly. The fundamental semantic restrictions of one and the simple functionality of the other are both traded off against horrible scaling relative to a technical project’s complexity and scope.

If you write a project with complex stages/components in those kinds of languages (or mimic their styles in Lisp code, for that matter), either you have to split those components into parts that don’t make sense separately (making the code base significantly more complicated than eg an equivalent Lisp codebase), or you have to write extremely long and convoluted programs to accomplish conceptually simple functions (making the code base significantly more complicated than eg an equivalent Lisp codebase).

Similarly, if you use the Python or Assembly coding paradigms for large projects, you quickly get lost in a sea of individually simple-seeming code segments, unable to grok the connections between said segments just because of how many things need to be kept track of.

In contrast, for Lisp languages:

A) The default style used by Lisp programmers is highly functional, using many higher-order functions, using macros that solve their problem-domains without explicitly exposing the code doing the solving (objects also fall into this general role, btw, which is apropos given the Common Lisp Object System was defined purely with macros), and clearly delineating code / systems with mutating effects.

While this style is admittedly harder to grok than Python/Assembly for simple cases, it has almost no reduction in reading-complexity as code scale/complexity increases. Complexity gets naturally encapsulated and automated by functions/macros/objects (as opposed to either a restricted subset of those or simply the developer’s own head, which are the 2 approaches most other languages offer for complexity management) (algebraic type systems are a very cool exception to the prior note, but a pervasive object system (like CLOS) paired with macros allows you to make a type system (like Coalton) without feature/ergonomics loss).

B) Interactive development and ergonomic DSL creation are objective wins for complex or large programs; the former significantly reduces iteration time for both cases, while the latter makes it easy to just write code once that addresses the complexity/scale of the domain and then never deal with that complexity again (or at least not with the full complexity, even if you don’t understand the domain well enough to obviate the irrelevant complexity entirely in your DSL).

Sure, hot-reloading in a few other languages gives us most of the former (although things like CL conditions, debugging REPL-layers, access to object contents & stack-frame inputs (only addressed by some debuggers, and only in a restricted way), and some other features still lack equivalents) and other languages generally use objects alone to address (most instances, though not all, of) the latter (rather than Lisp’s mix of macros/objects/higher-order-functions) (we’re ignoring the text-templating macros in languages like C++ because everyone agrees they’re more trouble than they’re worth).
But Lisp is still by far the most featureful and ergonomic offering of both of these facilities.