For me, it's been several events over several years.
The first was 1998. That was the first time I could confidently send a client to a big box store to purchase a computer that was appropriate for their needs, reasonably reliable, and a couple hundred cheaper than what I could build it for.
The second was 2000. I was writing up a browser related document about cookie management.... when I decided to look something up on the web by searching "cookie", I discovered Nieman Marcus had displaced all relevant technology discussions. For me it meant Joe six pack and the related marketing types had escaped the boundaries of AOL and taken over much of the Internet.
The third was 2004. While working on a new platform for one of the big 3 American wireless telecoms, the sponsors for the project made the decision that usability and reliability was less important than "entertainment potential". And yes, this stuff is located in the call path.