Way too many people advocating for hydrogen vehicles seriously have an idea in their mind where they just pour hydrogen into a their current vehicle, and it'll still make the comforting brr-brr sounds they're used to.

They don't actually want a hydrogen vehicle, they just don't want an EV and use "hydrogen is coming Soon(tm)" as justification for it.

People have actually looked seriously at what a world of only EVs would look like. It is basically a disaster of unsustainable resource consumption. Hence the need for hydrogen cars. EV believers have their own misperceptions about what is a good idea and what isn't.

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Should be noted that fuel cells are batteries. We can already eliminate this problem right away. But we must "wait" for future batteries for no reason at all.

No, fuel cells consume fuel; effectively they are oxidising it in order to make electricity directly. For a hydrogen fuel cell, you still need to add hydrogen when it runs out. Whereas a battery (in the accepted usage of the word) is self-contained - electricity can be pumped in to recharge it, but no fuel.

Fuel cells do not consume fuel. It converts hydrogen and oxygen into water. You can reconvert water back into hydrogen and oxygen. You can conceive of a fully closed-cycle system for this.

But it's not worth it, since you are just carrying a big tank of water for no reason. It is a smarter solution that a battery which does carry everything at all times.