>But it does, there is plenty of uncertainty: you can have a long sentence that wraps multiple lines, includes quotes and maybe code snippets with . inside them or just ..., so you can't easily tell where a sentence begins and where it ends.

If a sentence of length 'n' resides on a single line, wrapping on-screen, deleting the sentence is just 'dd'.

For more specific cases, Vim has three different visual highlighting modes that share commands one can apply to visual highlights. So in your example, I would initiate character-wise visual mode with 'v', type 'f.' to extend to the first period; then just repeat this until I found the extant period I wanted to include in the selection by pressing 'f.' as many times as necessary in the most vulgar case; or extend that selection to an obvious symbol near where I want to go, likely the one initiating an inline code block, so 't`' while in visual mode, placing the selection to the left of the opening inline code delimiter.

I've dabbled with Helix, a Kakoune-like, and it does not eliminate this problem of nested selection terminals; you're still required to trial and error since you can't immediately grok the coordinates of the nested period symbol you want to select to; both Vim and Kakoune's inputs only cover a first level.

There are popular extensions in the (neo)vim ecosystem that like EasyMotion that add ephemeral motion targets relative to your cursor position. I'm sure Kakoune has an equivalent. But there's no loss of behavior IMO between Vim and Kakoune here.