I agree and I would not call all dependencies a form of tech debt. They become debt only when you need to replace the dependency to do what you want to do. At that point the work to fix a bug or add a feature will fall to you, and it will become a debt. However to preemptively call all libraries technical debt rubs me the wrong way, combined with the author saying debt is always a bad thing. I always see debt in that context as “work that was put off”.
On the other hand, if you don’t use libraries you’ll end up with an enormous pile of technical work to do, likely outside your core-knowledge, just to get your project off the ground. Nobody can afford that, and you need to borrow from existing libraries to get your app off the ground. In that way it could be analogous to debt, but in the way that debt can be good.
I also don’t see dependencies as technical debt. In many cases they are the best implementation of a thing for that Language/Framework. Take react-navigation which is the de facto navigation library for React Native. You could argue that it should just be a part of RN but can you really make the argument that reimplementing navigation is going to give you less tech debt than pulling in this lib.
On the other hand, if you don’t use libraries you’ll end up with an enormous pile of technical work to do, likely outside your core-knowledge, just to get your project off the ground. Nobody can afford that, and you need to borrow from existing libraries to get your app off the ground. In that way it could be analogous to debt, but in the way that debt can be good.