IDK if I'd call that an "omission." There was a political system, and Hitler came to power within it. France still has a political norm of banding together to defeat populist far right parties, and an electoral system that lends to it.

The fact remains that Fascism, Hitler, and Nazism was popular and that was key to achieving power . This is essay is about that. Why, despite promising burdens and hardship, was Fascism popular. It just isn't about electoral tactics, negative politics or such. I'm sure he would have conceded the point that any given elections could have been determined by such tactics.

I agree with Orwell. The tactical-electoral subject isn't really that interesting, even if it is/was consequential. The point about promising voters burdens, hardship, & "military virtues" is interesting.

For example, I think this gives us clues about Russian communism's decline (also in the West, ideologically) after Stalin.

^Also I doubt Orwell was against "popular front politics." (a) I've read a lot of Orwell and can't recall any statement that suggests this and (b) Orwell himself volunteered in a communist militia against fascism. He himself was a socialist. If you're willing to join a communist militia to fight fascism, surely you'd be OK with joined ticket.