Adopting a new tool is hard. It means changing your workflow.
Even if the new tool is 100% feature overlap from your old tool and contains all of your data from the old tool (never the case), you still have to remember to grab the new one.
At scale, only social pressures overcome the friction workflow change. (With the exception of the CIO-mandated purchase)
This explains why collaborative tools like Notion and Figma can grow so quickly. Once the first person creates something with the tool and shares it with someone else, the social pressure is to keep using the tool.
Something to consider as you build a tool:
Even primarily single-player tools like Obsidian are driven by social forces: YouTube videos, tweets, plugins, friend-demos-friend, etc.