[allmadhare]

Maintainability and performance are often at odds, but that doesn't mean you should throw out one for the other in every case, and I don't think that's what people like Robert C. Martin were ever intending with Clean Code.

It's like database denormalization, it may violate normalization principals but it when applied to a well designed database is a valid optimization technique when done with proper understanding of the implications of said optimizations.

More importantly though, we are willing to sacrifice raw performance for developer experience and higher maintainability because developer time is expensive, and most stakeholders would prefer that you can add feature xyz in a reasonable time, over feature xyz running marginally faster. If ease of development and maintenance weren't important, we'd just write everything in assembly and bypass all these abstractions altogether.