I'm convinced that flat got popular because it was cheaper than creating textured graphics. The endless fawning over flat on HN was extremely obnoxious - back in 2013 you couldn't go a day without a "flat design is good design" post ending up on the front page.

Glad to see that there are other people out there who hate it. If there's one example of comically dumb flat design patterns right now, it's that "filter" icon you see around the web that looks like a solid-colored upside down triangle and nothing like a filter.