No doubt, as computational supply increases, so does the demand. Normally, this is a sign of health/progress; it only becomes a problem when demand shoots so far past the supply that we actually regress important user experience metrics (e.g. interaction latency or battery life experienced by the user). So why does this happen?

"HTML5" has rightfully exploded in popularity. In fact, these days it's hard to justify NOT building your front on this stack. But much like any explosion of a popular technology, the developer community will tend to push the limits of what it can reasonably do. This exploration is a good thing, but it can be frustrating until people settle into best practices of what applications do and do not suit a given tech stack.