The advantages of this:

- Every website has the same accessible layout

- Blocks advertisements

- Blocks popups and auto playing videos

- Blocks cookie banners

- Blocks newsletter signup modals

- Blocks sticky headers and all distractions

- Auto dark/light mode on all websites

- Choose your preferred colour theme, font, font size and margins and it applies to all websites

- Images are presented neatly

- Inline videos are presented neatly

- Space bar to scroll down, shift+space bar to scroll up

- J/K to scroll between HTML elements (usually next paragraph)

- Can be disabled on a per-domain basis for when it's not suitable

The downsides:

- There are no downsides