Counterpoint: I can identify which part of the UI most of those come from. This level of variety between various UI functions is actually good. I don’t want the interface tabs or the settings tabs to be confused with tabs in the store, even though they are all tabs. I don’t want buttons to all look the same, especially not the huge purchase button. But even accepting that as an outlier I want some buttons to be clearly part of the steam UI and some as part of the site page I am on, so I don’t get confused.
Counterpoint: I can identify which part of the UI most of those come from. This level of variety between various UI functions is actually good. I don’t want the interface tabs or the settings tabs to be confused with tabs in the store, even though they are all tabs. I don’t want buttons to all look the same, especially not the huge purchase button. But even accepting that as an outlier I want some buttons to be clearly part of the steam UI and some as part of the site page I am on, so I don’t get confused.