You do get immediate return on doing this. In art it is common to ask for critique-- it immediately improves that particular drawing (hey mate, you should maybe fix her nose, she looks like a pig) while also helping in the long run (okay I won't draw noses like that anymore).

It's not like you have to put a crown on everyone's head. The article goes really into detail, but it basically boils down to "Take turns." It encourages everyone to engage without talking over each other, avoids shying away from ever presenting your work, or going onto long rants. Which are things the author has mentioned has happened at other companies. Even in a small 3 person group, it's easy for one person to dominate the conversation. You don't want that. You want to utilize everyone's perspective and skillset. Three heads are better than one.

Sometimes a little bit of ceremony helps change existing behaviors and gives people with different perspectives the opportunities to speak up.

So far from true. At a startup, everyone is blunt, because it pays to be. Everyone there is counting on success.

Whereas at a corp, the ceremony was created by someone else who may not even work there anymore, for some superpsionic reasons that everyone basically just shrugs at because they don't want to lose their jobs. It'a a sludsgefest that startups can skip - no point in needless vagaries when in a startup, it's actually appreciated to collaborate organically instead of being culled for doing so.

So much of that response is utterly loaded with flawed assumptions. The irony is that your response is exactly why sometimes it's important to be cognisant of how to conduct critical conversations. It's not about "needless vagaries", it's actually about direct and on-point critique, without the loaded value judgements. This isn't a skill that tends to come naturally to people, that's what the "ceremony" is for.

A startup is not the place to have a personal journey of growth. It's a place to figure out an awesome thing to make and turn it into money. A startup isn't a class group project. That doesn't mean it should be adversarial like Linus Torvalds treats Linux kernel developers. But that's a far cry from expecting other people on your team to speak up and put in their contribution without needing to be prompted.

That's also making the false assumption that the only way to make an awesome thing and money is to expect everyone else to behave like yourself. The reality is that creating something that's truly amazing takes a variety of perspectives and personality types and sometimes actively cultivating that is critical, even in tiny teams. Mind you, if you only hire people exactly like yourself that solves that problem fairly well for the first year or so.

Timid people are not a protected class. This isn't a diversity issue. Bringing it up is just muddying the waters.