Sadly this is true. Canvas is still very much in its infancy. I see two main issues with Canvas for games right now.

First, canvas really needs to be hardware accelerated (someone already does this, Microsoft?). Having a few objects move around should barely take any CPU but with Canvas today it can be anywhere from 10%-20%.

Second, their needs to be game engines/abstractions on top of Canvas. Most developers don't want to have to write there own render/clear loop with all the utility functions to do movement, render shapes, texture elements, and keep object state. I know their are a few out there now but they are no where near the quality needed. This second step will not happen until my first point (HW acceleration) is in place.