OK, but using a pictorial sequence (flowchart) to show the how-to is an OK method
--unfortunately many people neither know nor care how-to (install an OS): they may not realize they need to partition and format the hard drive or even how to select a hard drive
Having bought a notebook or desktop or tablet with a pre-installed OS already running
--usually windows OS (some version)
A description in language of the steps needed, eg step 1., step 2. and so on could also work, except for the same reason
--many people don't/can't be bothered to read instructions
It's the same deal-breaker, when trying to assemble furniture or any other device or forgetting to install the batteries
RTFM is the UNIX/Linux refrain sometimes for these inevitable slackers..
--and that is a legitimate complaint, people should read the manual.guide/how-to or install instructions if they want to have a pleasant experience
If you know the steps needed, there aren't many surprises; with a little research..