Because that's where the real techy developers are who knows quality from marketing. Enterprise is filled with consultants so of course they promote Azure - what else are you going to do if you are a Microsoft consulting company?
Every single testing I googled, including my own results shows Azure, surprisingly have the fastest instances, CPU, SSD Access, and Network. They do lack a few other managed "Services" instances that made Google and AWS much more attractive.
Why is Azure not quality?
Azure is not bad at all, but in my opinion AWS still has more and better offerings.
Funny, then, how we don't keep hearing about big Azure outages like we do with GCE and AWS.
Because not too many people use Azure?
To be fair, all cloud environments have (major?) outages. Do you have data to backup your claim?