They don't ban sale of videogames/movies based on age rating mechanism, they restrict the sales. These words are not the same and not to be used interchangeably.

And it had taken many decades to produce a workable system within this medium. With the speed of government vs the speed of development in the private sector, a temporary ban whilst they get their ducks in a row seems wise.

Government isn't involved in that. Game and movie ratings are completely private industry practices. Your selection of distribution channels will be reduced if you don't go through the ratings process, but the government won't stop you.

For the US, yes, but some countries are more strict and do require some rating before a game is able to be legally sold, for example in Austria and France.