At the time desktop Linux projects like consolekit were an unmaintained mess, it needed replacements. Systemd also supported cgroups V2 and people really wanted to use that. No conspiracy or underhandedness required.
I don't think anyone would ever object against systemd as a project, it would make as much sense as objecting against, say, GNU Chess. All software has bugs, and they're gradually worked out. But the way it was introduced that made many people upset.
The way it was introduced was that many people could see the value in cgroups V2 and being able to drop unmaintained projects. Maintainers of distros and projects sometimes did this against some users wants, but in my opinion there was just lots of baseless complaining without creating an alternative.
