I find it much more convenient to press a button that's already under my thumb and then press a button that's already under my middle finger (for example) to get a symbol I want than move my hands from their typing position to get a symbol. It takes some time to adjust but I'm at about the same speed I was on a standard keyboard while using a corne (like the lily58 but with no numrow and one fewer thumb buttons per side)
Also space is right under your thumb as well, and shift can be in its normal place
Convenience is often a tradeoff for power. Nobody is claiming that vi and its derivatives are convenient, they're saying it's powerful.
Personally I'm much much faster using neovim than I could be using something like vscode. There's a myriad of other benefits that modal text editing brings to the table, not having to use a mouse and constantly switch back and forth being a big one for me.