No, "wrong situation" refers primarily to an application being added to the server. And not necessarily a full-blown business app either.
Say, instead, Java applets are added to the server. Java applets require a JVM. A JVM uses a relatively large amount of RAM.
Or say a (large) virus checker is put on the server [not preferred on a SQL Server, but some companies demand it on *every* server]. Or a larger e-mail client. Or a combination of them and perhaps others, such as Winzip, etc..
If you don't understand how SQL's memory allocation works, you probably will not investigate more fully to determine if the other memory usage exceeds SQL's nominal allowance for other uses. Maybe it's OK, but maybe not. The key is that the DBA needs basic understanding to even realize that it needs checked.
SQL DBA,SQL Server MVP(07, 08, 09) Prosecutor James Blackburn, in closing argument in the Fatal Vision murders trial:
If in the future, you should cry a tear, cry one for them [the murder victims]. If in the future, you should say a prayer, say one for them. And if in the future, you should light a candle, light one for them.