"nobody is going to say it's bad"

It's not about saying "it's bad". It's about talking about what might be better. Flat hierarchy or not, anyone should be able to bring up the topic.

And if you can't, that's a bad place to be working. There should be some kind of trust between people.

You don't need any kind of hierarchy to have real leaders. Every where I've been, you just step up and try to make it happen. Most of the time a bunch of other people are going to "thank you!". It won't always work and you can be diplomatic in how you approach it. But just make it happen and stop waiting for someone else to do it.

And if they, whomever they is, don't like it, move on.