How would ephemeral identities have a Web of Trust?

That's the point. You can't use ephemeral identities.

I think client side heuristic spam filters would go a long way. Also just a working block command is necessary

We have been down this road on nostr. Its not enough.

I don't think that's what we're building. We want to talk to everyone in a location and people you don t know. There is no concept of following. You're thinking about a Twitter clone with feeds and follows etc. Let's play it through: How would it work in your mind? You travel to SF and you want to know what's up on SF. You have 0 friends in SF. Vice versa, you're in Tokyo. You want to ask all your neighbors where the best events are today. You don't know who's loving around you.

wot doesn't work if you want to talk to the world

WoT doesn't change any of those goals. It would just filter out all of the spam out to just people that have follows in the rest of nostr. We went down this road with Around me and many public chat specs in nostr. Only wot can save you from the spam.

Sure, but does it not help at all? What's wrong with having multiple layers of spam blocking? It doesn't have to be effective, just not useless. Even removing 30% of the worst spam is better than not. And this is much more relevant to bitchat than amethyst.

Spammers are scripts running on desktops, sometimes with GPUs, wired to a power outlet. There is no way battery-based systems can beat them. All you are going to do is to waste people's batteries. We implemented pow on amethyst, but it was clearly draining way faster than what we though it would.