Yes a JetBrains IDEs will take longer to build the AST model in RAM but once you have it they do amazing things with it. E.g semantic search and replace, etc. The debugger capabilities are spectacular, they literally show the values of variables on the side of the line you stepped over. Another cool thing, inferred types just show next to the variable definition, parameter names appear in the method call, etc. These are small things that add up to a lot on the day to day.
About projects. JetBrains do create project files but don't require a project structure in newer versions of their IDEs.
The problem is that IDEs are very simple to pick up and people stop after that basic usage. They have depth that exceeds emacs in some respects.