JavaScript-based UIs are fundamentally more challenging to own and operate because the limiting factors on their success are outside the data center and not under the control of procuring teams. The slow, flaky networks and low-end devices that users bring to the party define the envelope of success for client-side rendered UI.
This means that any system that puts JavaScript in the critical path starts at a disadvantage. Not only does JavaScript cost 3x more in processing power, byte-for-byte, than HTML and CSS, but it also removes the browser’s ability to parallelise page loading.
