And the browser UI is quite pointless for them... Why even have that? Is it only there to increase the metrics?

The shorts browser UI is a clone of the tiktok UI. I don't really like either, they could have innovated at least a little by introducing more powerful video controls like the seeking shortkeys that work on youtube for example.

But it wasn't built to appeal me (or you), but other parts of the population, people who prefer tiktok like experiences.

For me personally, the reason to use shorts every now and then is because tiktok is authwalled while shorts is not. But I don't know what other users of shorts would say why they prefer it.

They prefer tiktok's content and recommendation system.

Just trying to recreate some of the UI aspects of it is just cargo culting.

That's only if it's a vertical video. Most videos on YouTube are horizontal.

Sortaaaa. I’ve seen horizontal videos that, in the past were standard videos but under 60 seconds, and they were cropped down to Shorts compatibility.