The main cause why modern computer users are shy to start an analog Zettelkasten is because they are believing in the myth of a highly efficient electronic data. The assumption is, that typing something on a keyboard is very fast and that URL and bibliographic references can be added by simple copy&paste to the knowledge database.
The underlying assumption behind the average Obsidian PKM user is, that there a no costs at all in creating all the nodes in the second brain while in contrast analog note taking is perceived as very complicated. The understanding is, that for creating an analog note somebody has to search endless time for a pen and needs lots of hours until all the index cards are written in long hand.
It is a widely known fact that Niklas Luhmann has created all the 90k index cards by hand. But Luhmann has worked in a time before the advent of the IBM PC. The prefered way of creating a Luhmann like Zettelkasten since the 1990s is of course a modern Windows or Linux computer which has many advantages of a luhmann style note taking system.
To get a better understanding why analog note taking is even in the year 2023 the most effieient way in creating a knowledge base, a short look in the figure may help. The spreadsheet compares the amount of data and the needed effort in minutes to create an analog vs. a digital zettelkasten.
The obvious difference is the typing speed in chars. It is a fact, that a computer keyboard allows to type in something much faster than an analog pen. On the second hand the difference is smaller than expected. If the user is reducing the amount of written of cards for each byte and also reduces the amuunt of daily cards he will need less overall time for creating new notes.
Let us slow down the situation a bit and describe why digital notetaking takes so long. According to the table lots of cards are created each year. Even if the typing speed is high, these cards are requiring manual effort. The user has to invest around 64.4 hours per year to write down 1095 digital note cards. It is not possible to reduce the needed time because there is a limit in the typing speed on a computer keyboard.
In contrast to a famous myth, the amount of effort for creating a digital card index is not zero but it will produce endless amount of hours in which the user has to type in something. And the example with only 3 newly created cards is simple one. If the user puts more effort into the Obsidian PKM software he will need more hours.
The main advantage of analog note taking is, that the user knows in advance that it is complicated to write in longhand. So he will think twice before he creates a new card and will reduce the information to a minimum. This allows to reach a higher productivity than with digital note taking. In the figure the overall needed time per year is smaller for analog note taking. That means, Analog note taking can safe time compared to digital note taking.
The main cause for the paradox situation is because of the slow typing speed in general. No matter if a human is preferring an analog pen or a digital computer keyboard, the possible speed is very slow. A typing speed of 170 chars per minute is equal 23 bit/s. In comparison, outdated analog modems are using 14400 bit/s as the average speed. Even if somebody is able to type in something very fast, his writing speed ridiculous slow. The world record on a computer keyboard is around 800 chars per minute. That means even the best user in the world will need endless amount of time until 1000 and more nodes in the Obsidian PKM software have been created.
The assumption is that the slow typiong speed in general plus the small difference to analog writing speed explains why a paper based Zettelkasten makes sense. It allows to use the ressources in an optimal way and avoids wishful thinking. Humans, no matter if they are prefering analog or digital note taking are not capable in creating hundred of index cards every day but in the optimal case there are only 2 or 3 newly created cards possible.