When you dig into productivity tools, it's easy to fall into the urge to use an all-in-one tool. For example, doing absolutely everything in Notion or Obsidian. People also try to hook up integrations between apps until the whole setup is dangling with them.
People interested in this area care a lot about efficiency, so using one tool seems more efficient than using several, and I think that's where the tendency comes from. But the all-in-one tool is a trap, because it doesn't take into account the mood of using specialized tools.
Have you ever seen a craftsperson use only one tool? A beginner might use an all-round tool, but the more skilled they become, the more they use the right tool for each situation. Knowledge work is the same: as your skill grows, the number of tools you use grows too. This is partly because of each tool's special features, and partly because each one feels different to use. When I use Obsidian, a calendar, reminders, Jira, or Confluence, each one gives me a different feeling.
And this is just my own bias, but of all the tools that bill themselves as all-in-one, I've yet to see one that does its many jobs properly. Everything is there, but every feature has a screw loose. Whatever the company, the manpower for building a tool is limited, and limited resources can't satisfy every requirement. So software that claims to be all-in-one is very likely a mediocre product.