It favors the status quo and unobjectionable actions
It makes people more reluctant to voice disagreement, because voicing disagreement is coupled with a costly process of reaching consensus on that topic (whereas if decisions are made by an executive or a vote or something, voicing opinions doesn't have to slow things down)
It means when there's disagreement, decisions are made via one side politely acquiescing or getting exhausted; that's cursed
Inspired by @habryka, but he may have different reasons.
As someone who grew up Quaker and spent a lot of time in consensus process making group decisions... I disagree strongly. I think consensus process done well is fantastic for certain specific situations.
* where there's a strong sense of community and everyone genuinely cares at least a moderate amount about the preferences of all the others, and trusts the others enough to voice their true opinion and emotions and worldview
* no more than about 50 people, physically in a single location
* the question being deliberated upon is worth the effort of several hours of intense focused attention from all participants, and everyone is willing and able to commit to putting in that effort, and knows and agrees to the consensus process
* a good process-leader (aka Clerk) does a good job of paying attention to the body language and emotional tone of speech and the logical flow of the discussion, and can highlight omissions or guide the group towards a different focus, ushering the process towards clarity
This is a lot of specific requirements though, and I think breaking any one of them can make the whole thing work out poorly. It's less about exhaustion and more about extending radical empathy and careful listening to really understand someone else's viewpoint on a gut level, figuring out if they are lacking information or if you are, being willing to spend the time and effort to really truly get everyone on the same page mentally and emotionally. To bring the group into alignment on viewpoint.
If you don't do this, I wouldn't really call it true consensus. More like 'fake handwavey consensus' which does have exactly the problems you describe.
Yes. Sorry. Upvoted. Instead of "consensus bad" I should have said "consensus often implemented bad" or "think about your process for resolving disagreement, and in most contexts be very wary of (1) getting hung up on minor disagreements because you don't have a salient process for moving on, (2) needing inside-view buy-in from everyone, [more]" or something. I should have given central examples of failures, like "you spend half of a meeting talking about something that clearly isn't worth that, because there's no clear good way to move on."
Sure, then in practice that's just democracy-with-vetoes. I'm criticizing actually trying to reach consensus, or where there's no normal/salient way to move forward given disagreement besides talk until there's (nominally) consensus.
Oh, I should have included examples. Like, if I'm cowriting a doc, maybe the default is we don't have a process for moving past disagreements; if neither of us changes their mind, eventually someone acquiesces, but many processes for moving past low-stakes disagreements would be better.