I think you're glorifying the past. Historically, conformity was more enforced and more important for survival, but for many individuals it was likely more oppressive and limiting. Memes were (and are) a mix of adaptive and random, attached to each other in hard-to-identify-in-the-moment ways. For cultural norms, the various equilibria of different groups and behavioral/belief norms shift in ways that are a mix of adaptive and not.
Conformity is reliable only if the following is true: you are close to the median accepted member of the successful group with which you're conforming. For outliers, conformity is not an option - either there are personal psychological reasons it's hard to conform, or the normies will notice and prevent you from getting the benefits of membership. For members of less-successful groups, conformity with your group only brings group-level benefits, which aren't sufficient in today's information environment.
This has ALWAYS been the case, it wasn't that different historically. The main difference was that prior to 1920s or so, many members of less-successful groups didn't know it, or didn't think there were other options.
I'm not the person who wrote the linked post, but you can you add your comment to the Substack post if you want to talk to the author himself.
We are social animals, and conformity is part of our social adaptation. We imitate others. This imitation is not just superficial. It is deep. We imitate the structure of knowledge in other brains. For example, you learned language by absorbing knowledge from other people. That knowledge is subconscious. You use it every time you interpret or generate language, but you have no conscious access to it. You absorbed it subconsciously, and you apply it subconsciously.
In the past, conformity was a good heuristic. Common memes were probably adaptive. If a meme was harmful to its hosts, they would not prosper. So, if you imitated the successful people in your community, you would likely be successful too. People lived in small societies, and they lived close to nature. Their memes were regularly tested by reality, and by each other. False beliefs could arise, such as religion, but such beliefs were tested for their adaptiveness. It was hard for a maladaptive meme to spread.
Conformity is unreliable if any of the following are true: 1. Most people are crazy. 2. You can choose your social circle. 3. You are exposed to artificial people. (see the rest of the post in the link)