Those “fans” have forgotten how previous flight simulators were at launch (all of them) or they’re at their first rodeo.
This is pretty much the most complex piece of commercial software on the market today. It’s ludicrous that some expect it to be spotless at launch. A lot of the whines on the official forums are painful to read. They feel like a five-years-old pretending to be a “pro simmer” wrote them.
Incidentally, the author of this article, while correct on most accounts, mentions that the sim had “game-breaking” bugs at launch. None of the bugs are or were “game-breaking.” Most were minor annoyances and there was basically nothing that couldn’t be worked around.