I've done primarily FE for the last several years and the argument I make with my BE peers is that our BE-focused industry focuses on coding for extension, while a well-run FE codes for _replaceability_. Because, for reasons that are NOT limited to a regular rotation of libraries and frameworks, our code will be replaced frequently. Our requirements change so frequently that no amount of extensibility will manage the paradigm shifts.
That's not a BE vs FE issue anymore - Many of these growth-oriented companies and startups are making dramatic changes in tech/approach/offerings and other basic requirements. Being able to pivot quickly is beneficial. Allowing a team to try out something and work out the kinks (while still producing output that can be used in production) before everyone else considers adopting it is really beneficial.
So in the sense of dealing with that reality, in avoiding being the company running on Java 8 or jquery 1 or heavily commited to their SOAP infrastructure or deeply coupled with a UI interface that everyone rolls their eyes at - yes, you can call these cases "successful".
If those issues aren't your biggest issues, if you have a stable collection of offerings and are interested in solving scalability, focusing on extensibility, etc. If you want to have a rigid set of UI standards and have confidence that those are being universally applied...then no, they aren't "successful".
Appropriate tools for the appropriate task. In this case, it's easy to see the result as the failures it contains and not consider the failures it has avoided.
The AWS console is a jarring experience due to this and, in my opinion, not very well done. Every service has a different theme and it is generally ugly.
From a business standpoint, I doubt many people are turning away from them just because of this though.
Although which Amazon product wasn't specified, the AWS console is a shining example of something that does micro frontends badly.
To your point about respectable customers using the API, according to Amazon the majority of customers use the web interface for most things. I forget the number mentioned at the AWS Summit, but it was significant.
Even I work full time on AWS and do most provisioning via API actions, but still end up in the console tracking down various things since the API is very cumbersome.
That's pretty specious reasoning though. Google, Wikipedia, and Youtube are the highest trafficked sites and I'd argue have a bit more visual cohesion.
Just because successful companies do a thing doesn't mean everything they do is a success.
Well, what's your success metric? I'd argue that neither of them would have been able to implement the rich features they have at the speed and scale they've achieved - features that have given them market domination.
If pure aesthetics is your metric, then yeah, they're ugly. So?
Amazon's M.O. is "pay money, get physical item". On the scale of how much aesthetics matters on a website, that's way over on the "not at all" side. About the only thing I'd put further that direction is Craigslist (which is "maybe pay no money, maybe get physical item").
For nearly every other website, aesthetics is of significant or even primary concern. When I'm not receiving packages from it, I care about how it looks. Facebook, Google, and StackOverflow were all much cleaner designs than what they replaced, and Wikipedia is perhaps the biggest and most aesthetically consistent website there is. Aesthetics matter.
So then what is the cause of the ugliness? Is it inconsistent appearance between components? Or that it's too busy and cluttered, which would probably be true with a monolith as well?