Because a lot of people are speaking very authoritatively, yet with little content, about systemd. They raise objections based on partial or inaccurate information. Various bans on discussion are happening precisely because it's apparent that a number of people are no longer interested in useful discussion, so much as creating chaos until they get their way.
Manifestly described by the idea that people without time to interact with Debian, are going to instead launch their own Linux distro.
If partial or inaccurate information about a subject was the criteria for not talking about it then Torvalds should have shut up about kernels and let Minix be the default for everything. Read the exchange between him and Tanenbaum and tell me it doesn't sound like two douche bags flame baiting each other with Torvalds sounding like he has no idea what he's talking about: http://oreilly.com/catalog/opensources/book/appa.html
The whole point of free licenses is to let half educated monkeys type away on keyboards because every so often you end up with Apache or Linux out of it, of course you also get pulse-audio and systemd but no system is perfect. If people like it more than Debian it will replace Debian, like Ubuntu nearly did before they went with unity and a whole bunch of other terrible decisions, if they don't it will die, and if it sticks around as a project with some users, like every other debian derivative, it will be a wonderful resource to find bugs.
In which case we don't need to debate who's spreading FUD.
But people who want to take part in a debate should expect be held to account for the things they say, and in the case of systemd a lot of people are spreading a lot of misinformation. That's forgivable, I make stupid mistakes and misremember things all the time, but it's sure starting to seem like there's a very casual disregard for the truth and with it, any possibility of solid debate.
Not to mention the usual crowd of trolls who are just happy to have something that'll start an argument.
Manifestly described by the idea that people without time to interact with Debian, are going to instead launch their own Linux distro.