It wastes vertical space, most people have horizontal monitors. On mobile devices it takes up a lot of the screen despite them being vertical.

It sometimes breaks thing like "space" to scroll, depends where focus ends up.

I use it mostly for web interactive apps, I guess mobile is not really my use case then.

I'll be more attentive to space scroll tho.

Thanks for the comment.

Even on the Desktop Web Browser (where I was), by default the scrollbars are hidden (macOS). It is not apparent that the content is scrollable but confined in a frame/container. I had to stumble on it when I graze over the Magic Mouse because the cursor is outside of the content (inside the frame/container).

Contents inside a frame is OK but make it apparent, say, have a thin border, with a lightly different backgound and have the scrollbar forced if the content is larger than the defined height of the frame.

The scroll is not properly restored between browser navigations.

it's a major accessibility hinderance as well