Just like politics and the news, when you read of something being attacked, I think "who is saying this, doing they have an underlying bias against this thing they are attacking"?Why would someone speak-ill (attack) something they didn't have a bias against and were neutral on?
The question is not does a bias exist, it's if a bias is illegitimate. Many people who have issues with systemd have them because of their own experience, which they document. And often the very act of documenting their issues brands them as biased. When people say systemd is a regression and list their reasons, they are labeled as not having enough experience with systemd, and if they'd only give it a try, they'd see it's better. But that's the exact thing that's occurring, someone tried to do something that used to be obtainable, and their experience with systemd has been things being difficult, obscured, badly documented, undiscoverable.
If we're going to merely ask if attackers have a bias and use that as a reason to downplay or ignore their contrarian arguments, we should be asking if proponents have a bias and also use that to downplay and ignore their supportive arguments. "Are systemd developers in favor of systemd because Red Hat signs their paychecks?" is just as much an invalid assertion of bias, assuming the developers have made meaningful supportive cases that are independent of the bank account that funds them.