The latter is false because the APIs for image manipulation don't give you features like hardware video-compression-codec decoding, and so you just can't really drive a <canvas> fast enough using JS to draw video on it.
The JS graphics+SVG APIs, however, do have all the right primitives exposed to let you do flash-level animation. It's not a matter of incapability; it's just a matter of nobody having coded the right framework, or the right framework (i.e. the one Animate uses) being proprietary and without an open-source attempt to clone it.
That doesn't suggest browser vendors should step in and put the capability into the browser, any more than the inability to do realtime 3D without a framework like three.js or a game engine like Unity's HTML5+WebAssembly engine, suggests that browsers should create a common, native game-engine-like API.
It is like saying that you don't need native video support, but you use JS to interpolate initial image.