Why was my question deleted? I did not even get to see it in closed state, so I really do not know why.
(Also, a deletion being a moderation act, "removed from Stack Overflow for reasons of moderation" feels like a tautology.)
Short answer? Although well-written, your question fit the pattern of what are commonly called recommendation questions:
Answers to the question I link to describe various philosophical and practical problems with these sorts of questions, but to understand why your question was deleted we need to focus on just one of them: they attract promotional answers.
As Stack Overflow has grown over the years, it has become an increasingly tempting target for folks with something to promote. If you're trying to market a tool, library or framework, SO's acres of questions asking for tools, libraries or frameworks are too good to resist. It'd be one thing if such people limited themselves to answering questions where their product actually solved the asker's problem - especially if they also went on to describe how the asker and others like him could make use of the product toward this end.
But in general, they do not.
Cleaning up these posts is a time-consuming task for users and moderators, made all the more difficult when the promoters try to lawyer their way out of the hole they've dug. It's reached the point where, when a question starts attracting these sorts of answers, it is more expedient for a moderator to just delete the question itself rather than trying to preserve yet another honeypot.
And that's what happened to you.
Fortunately, there are ways to ask most of these questions that don't fall into the "recommendation" trap. Not explicitly asking for tool recommendations is a big part of that; being very specific about what you want also helps a good deal, since it's then harder for answerers to argue that they're answering in good faith when their recommendation fails to meet your requirements. Your updated question goes a lot further toward satisfying both of these.
In closing, I apologize for the lousy experience you've had with this question. You asked it in good faith, facing a problem many of us have also faced at one time or another, and didn't deserve what you got in response to it. We're working on tools to make communicating such unexpected nuances a bit more obvious and easier to recover from, but for now just know that this rather severe action wasn't directed at you but at the folks who've made it their business over the years to ruin this particular type of question for everyone else. Sorry.