Nothing ages you faster than remembering when scrollbars were chunky, reliable parts of the browser window that just sat there doing their job. Now we've got these fancy disappearing overlays that show up for 0.5 seconds before fading away like your hopes of maintaining backward compatibility.
The real tragedy? Watching the frog age from "young dev with bright eyes" to "senior engineer who's seen too many UI frameworks come and go" in the time it takes for browsers to decide scrollbars should be ephemeral experiences rather than functional UI elements.