Would you know any tool to quickly create such onboarding animations?

This one looks like it's done with GreenSock, but you could probably get away with using Abode Edge Animate (more WYSIWYG, Flash-like editing experience).

This talk makes so much sense. https://www.youtube.com/watch?v=X1nNkS4SVRw

I first thought the article is written on similar lines of sarcasm.

Browsers could take note of this and clear the previous page only when blocking resources(CSS) finish downloading instead of current: First byte. This should make us see less of those white pages.

Add to this- websites unnecessarily sticking table headers, navigation menus, sidebars (gmail!).