Windows 98 wasn't composited, which makes a huge difference.

And to be clear, there's a ton of unnecessary bloat today as well. It's just that even a lean and mean highly hand optimized native app is gonna be way bigger today than it was then, due to compositing, higher resolution assets, higher resolution screens and different design sensibilities. But most apps aren't lean and mean highly hand optimized native apps so.

Compositing means you can excuse an extra dozen megabytes per megapixel of window size. The window in the article is less than a megapixel. That factors in the relevant part of screen resolution too. High resolution assets should scale alongside window size too, adding a fraction of the above dozen megabytes.

And I'm saying 98SE already had image-heavy design sensibilities all over.

You don't have to highly hand optimize to run a weather UI in a lean way.