We keep building from what we assume is the best. If a popular site goes with flat design, it leads us to believe flat design might be attributing to their success. So, we try to follow suit with trial and error. If flat design is working for them, maybe taking it to an even more extreme and reducing all images and gradients will leave us even more successful. Or, maybe only some aspects of their flat design are contributing to their success, and it's a balance between flat and non-flat elements.
Which is best? No one knows. We'll try all the possible combinations, and gravitate towards what's successful with profits, and with users. You can't expect these changes over night. Right now designers are quite sure the future involves more minimal design. The only way to test this is to experiment with different combinations.
So, don't piss on someone because they try an extremely flat design and it fails. The only reason we know it fails is because they went out on a limb to try it out. Instead, thank them for trying, look towards any aspects of their design that did work, and improve on their failure. I can guarantee we're going to have an even better experience browsing the internet 10 years from now. It's going to happen because of many designers and developers failing, and few standing on them and succeeding.
Other designers started to notice. People started blogging about the "flat design movement" (which didn't yet exist, but nevertheless made for a great headline). Some designers agreed with the sentiment and copied the style.
Then, nobody could deny the impact of flat design. It was everywhere.
But for every designer out there, there are hundreds of imitators. They call themselves designers, but all they know how to do is clone a certain look. They are like the skilled painters who make forgeries of famous paintings, but can't paint originals. They started copying the flat design they saw everywhere. Except they didn't understand the principles behind flat design. They used it where it was not appropriate. They took it to absurd extremes. They disregarded readability, usability, and originality in pursuit of a certain look.
So now you have the same bad design everywhere.
Design fads exist because most most web designers are really imitators. They don't tailor a solution to fit the problems. They are just good at imitating other people's solutions. And since most founders / bosses / HR people aren't designers either, the imitators get hired.
Off the top of my head, I'd think there's a lot of Apple / Steve Jobs mimicry in the use of flowery language.
Everything your local startup produces is beautiful just like everything from a new Apple store to an app, a document or a template in a WWDC keynote is beautiful and everything Apple does in general is 'incredible', 'great' and 'amazing' in their own words.
Ask most people to name the second largest search engine, and they'll draw a blank. Google is the alpha and omega. This means that most tech and tech-adjacent business like media is at the whims of Google's search results.
So with the modern internet, as far as consumers go, it's mostly winner-takes all. This trickles all the way through to everything else, including VC investment, "disruption", and cargo-cult design. If you're not following the current zeitgeist you're kind of left in the dark.
As for solutions, I don't think they'll come from designers. You can't ask the soldiers to just stop warring. It's a systemic problem and requires a systemic solution.
I don't see people understanding this or rallying together to combat it anytime soon, so I think it will end like most wars do. One side wins and writes the history books to make it all seem obvious in retrospect.