For certain values of "unnecessary", yes. We've still got a few steps to go before we can decode an image with SIMD instructions (assuming FLIF can use those to speed up, though I imagine it can as any modern image format ought to take that into consideration), and I'm not sure what the story is for pushing images efficiently to the browser, but you should at least be able to put something together that works in WebAssembly now and speed it up in various ways later.