Perhaps a better response would be outlining how much memory it actually takes? This way people can decide (i.e. if they care deeply about the memory footprint)
The idea behind using S3 or other PAAS is to not run and maintain your own servers. While minio is great if you want to run your own S3, depending on it to use a different PAAS is not the most convincing use case
Serious question: why? I mean, maybe as a really, really lazy hack if you've got free azure credits and don't ever plan on actually supporting Azure in your codebase. But that seems like a very, very corner case. Would anyone ever actually do this for something production? Why wouldn't you just write native azure support, it's not THAT difficult.
I probably use 20-30 apps that support using S3 that I can think of right now. Not all of them are maintained by me or even open source. Other than a proxy, it's impossible for me to change some of them.
In terms of use case: my company has a customer that requires us to locate an instance of our product in Azure, and some of that infrastructure is much easier to move with a compatibility layer.
You might as well ask why there are any standards in software and networking at all, as each new protocol or library isn't THAT difficult to support.
https://github.com/gaul/s3proxy