Because TAB and SPACEBAR are different keys and should not be used for the same reason.
I always use SPACE bar to create white space and CTRL+SPACEBAR for creating 4 white spaces directly.
The TAB key is very comfortable to use it to jump out side the block and ENTER new line to start typing new code.
In CB it is working fine sometimes as I want it to be, But not all the times.
I can record the video to submit, I am not sure if this is a bug.