&quot;Rust&#x27;s ownership&#x2F;borrowing system is hard because it creates a <i>whole new class</i> of side effects.&quot;<p>I&#x27;d submit it doesn&#x27;t create them... it <i>reveals</i> them. They&#x27;ve always been there. Almost every other language fails to shine the light on them, but that doesn&#x27;t mean they aren&#x27;t there. All GC&#x27;ed languages still have issues of ownership, especially if threaded, and all non-GC&#x27;ed languages have all the issues Rust has... it&#x27;s just that the language doesn&#x27;t help you.