I think that’s unfair. While “sfinae’ itself is a mouthful, what it says in practice is that template expansion observes the principle of “least surprise” which is inherently user friendly.
You certainly don’t need to know the acronym, or even of the idea, to benefit from it. I stead, the developer won’t be presented with a confusing error message when the thing they want to happen is supported but not the first possibility examined.
The argument is I think, that because sfinae effectively added an "if" statement to C++ templates, it made templates turing complete. It made it possible to write all kinds insane, undebuggable programs purely at compile-time, in the most terrible purely functional language imaginable. People did exactly that, which went fine until their colleagues (or users of open source libraries) did something unexpected and got screenfuls of errors.
Wikipedia's sfinae page has a nice story about how it added compile-time introspection and conditionals to the language: https://en.wikipedia.org/wiki/Substitution_failure_is_not_an...
Sure you can write spaghetti code, but you can do that in almost any language. And there are popular languages that had explici design goals of limiting expressiveness in the hope of reducing spaghetti code (Pascal, in its time, and go today). I consider it like a balloon: without that power you end up with more boilerplate and repeated code, which to me makes following the code harder. But other people reasonably disagree.
Using a modern example, the way template metaprogramming started feels like return-oriented programming, or those "MOV is Turing-complete" or "MPU error handling is Turing-complete tricks". Someone figured out the standard unintentionally lets you make a conforming compiler do computations, and it ended up becoming an accepted feature, instead of updating the language to something resembling modern constexprs, or Common Lisp's compiler macros.
It's a clean, minimal, purely functional Lisp-like language. Nothing 'insane' or 'undebuggable' about it.
(Well, maybe if you're the kind of person who only ever coded Qt-style OOP C++98 in your life you might be shocked, but for the rest of us there is nothing surprising or special about C++ templates.)