because invariably you're going to want to recall this command from history and insert "grep -v HostnameIDontCareAbout" between the cat and the grep. or you're going to want to replace "grep -i 'problem'" with "awk '/problem/ { print $3 }". or you're going to want to do both.

people whine about 'useless use of cat' like it's still 1982, but the fact is that it's convenient for iterative development of a pipeline in situ and it costs nothing.