Especially in the case of having a buffline.
Within a tab you can split the viewport in windows to see multiple buffers at the same time.
Plugin use also windows within a tab to let you:
- Browse your files (e.g.: nvim-tree) or
- Browse your tags (e.g.: tagbar),
- Browse the undo tree (e.g. undotree)
With bufferline plugin you can switch the buffers visually (e.g. bufferline).
When you create a tab you restart with a new independent layout a bit like a new Vim in Vim.
Vimspector uses a new tab to create a new debugging layout when the debugger starts.
Some use one tab per project to have their specific window layout per project.