Hot take: I believe that 99% of people do not need a personal knowledge management (PKM) or "second brain" system to be productive.
However, I do believe that 100% of people should try out or research PKM and see if it legitimately helps them, as the barrier of entry to this practice is as little as maybe 30 minutes of your time and downloading a free application.
Give PKM a try and if it does not help you, I am certain you are not missing out on much. I believe that exposing yourself to new ideas and concepts is always beneficial, but you do not need to stick with some system if it does not end up helping you in some way. If you are an effective worker with the default notes app on your phone, keep at it, because if it works it works.
Everyone differs in the ways in which they think, learn, and apply what they know. I see a lot of influencers in this space touting PKM systems as a universal tool that everyone could benefit from, which is simply not true. These same influences are also typically trying to sell you courses or products, even when there are vastly more and probably better quality free resources out there for you to discover.
Another problem I see within this space is the trap of writing notes for the sake of writing them. If you just collect notes and do not end up using them, you are just wasting your time. I know that putting words on a screen may feel productive, but if you are just writing things down and never using what you note down, there really is not much point in writing it down to begin with. Having a complex system exacerbates this problem, as you end up spending more time wrangling your notes, switching between tools, and wondering how best to fit a new idea in your system. All of this extra work does not amount to anything if all that effort goes towards knowledge that never gets used, even though you feel accomplished by getting through this whole time-consuming process of just writing something down.
PKM bros advocate for taking extensive notes on every single thing you read, processing those notes, and working the ideas you learn into their own brand of complex second-brain system (that they'll show how to implement for a measly $250 or so). You really do not need to do that if you do not want to, sometimes it's nice to read an article without spending an hour taking notes and processing what you write. It's also nice to just quickly jot down an interesting or useful tidbit from what you read, you really do not need to spend huge amounts of time processing a single idea if you donβt get any benefit out of it. The human brain is a beautifully powerful machine, you will still remember important things without needing to write everything down.
A great article I recommend reading on this topic of toxic productivity/PKM systems is Sasha Chapin's Notes Against Note-Taking Systems.
I wrote this because I myself use a knowledge management system, but I find the evangelization in this space quite cringy. I like talking about knowledge management and advocate for trying out amazing free tools such as Obsidian (what I personally use these days) or Logseq, but I do not try to push these things onto people who are not interested in changing their already effective systems.
If you believe whatever system you use to get work done is lacking, there are plenty of very good free resources in the PKM space, as well as free tools to discover. Take a quick dive into the rabbit hole, and if what you discover helps you, that is great! But if it does not, that is fine too. Stick to whatever workflow makes you happiest and productive, and do not trust people who do not know you who say otherwise. You are probably not missing out from a community of people who talk about doing work more than actually doing it.