You'd get Office 2003 and it'd follow the Windows XP style with lots of blue [1] and you'd get Office 2004 for Mac with the brushed metal styling [2] - and many applications only targeted a single platform.
Whereas in the modern age you get Slack for Web, Slack for Windows, Slack for Mac, Slack for Linux, Slack for iOS and Slack for Android - and it tries to be consistent across different platforms, instead of being consistent with different platforms.
[1] https://en.wikipedia.org/wiki/Microsoft_Office_2003 [2] https://en.wikipedia.org/wiki/Microsoft_Office_2004_for_Mac
It was at win8 where everyone just noped out and just started doing whatever they wanted. XP/2000 was the last era where anyone really cared.