Very true, but content creation used to mean 720i. Doing high quality compression of 4K with the latest codecs is still a beast.
Pretty sure most of the encoding/decoding of video is handled with special circuits these days.
Now, add enough layers and it'll probably falter, but with dedicated encoding/decoding circuits combined with a modern GPU it will definetly be a usable experience with some lower res quick pre-renders at worst but probably realtime for most content creator usages.
The Macbook Neo has a 2.5x higher multi-core Geekbench score compared to the i7-4960X's, the top consumer CPU of 2013 (which could handle 4K video editing in h264), and its single-core performance is 5x higher. Plus, I'm 99% sure the MacBook Neo has a dedicated video decoding ASIC anyway.