We all use tools that are not “necessary”, but are very useful. Most developer tools fall into this category.
Thinking about the tools I use, there's not currently one that can be avoided so easily. The biggest tools I use now are GitHub, IDE, Slack, and GSuite.
The broader point was that yes, meeting discipline can be achieved by just sticking to certain practices. But a tool systematizes these practices and make them easier to implement. This is the reason we use most tools, even though we know that it is technically possible to survive without them (even if it would be very difficult).