Forth is at this point more of a culture than a language. It's a culture about keeping designs simple so that they're understandable. Without this, Forth is only powerful for programmers who can keep a lot in their heads, but lots of Forth programs end up being write-once. Moore's view, as well as most other high-level Forthers preach simplicity above all; a code cleanliness that would make Uncle Bob blush.

Lean and most type theoretic-based languages don't merely preach simplicity, they demand it. A function or type with a handful of terms or constructors might be provably inhabited/total, whereas one with 2 handfuls of terms or constructors might not be in a reasonable amount of time due to the exponential growth of the proof space. Factoring code optimally for provability yields the simplicity that Forth programmers are striving for.