Why do you need a secondary for something like Murphey's Irish Stout if you are not dry hopping?

Question

General consensus is that secondaries should only be used for dry hopping or added flavoring like fruit. The original idea behind secondary was to get the beer away from the majority of the yeast to keep from getting Autolysis flavors in the beer. However, your shop has recommended that you use a secondary.

Answer 1

Secondary and (also Tertiary) fermentation aid in the refining process of your beer weather it is an Irish Stout or almost any other style. Secondary fermentation will also help produce a much purer tasting beer. Please be aware that thorough sanitation is very important when racking a beer to your secondary (or tertiary) fermenter. Beer is much more susceptible to unwanted bacterial infection/contamination after the vigorous primary fermentation period. You also want to pick the proper sized fermentation vessel that leaves very little head room in your secondary fermenter which helps reduce the chance or degree of oxidization. Most beer styles, including Irish Stout, should be racked to a secondary fermenter in 3 to 7 days after the start of fermentation. A useful rule of thumb is to rack your beer to the secondary fermenter when you notice that your air lock is producing one bubble/burp approximately every minute. This lets you know that the primary fermentation stage is complete. You want to remove the beer from the yeast and sediment in the primary to avoid off flavors steeping into your beer. Excessive amounts of yeast will Autolyze/Cannibalize when it runs out of fermentable sugars. Yeast Autolyzation produces an undesirable flavor similar to burnt rubber.
Clarity in an Irish Stout is not as  important as it is in lighter styles of beer, but haze or cloudiness in a dark beer can cause the dark beer to look less dark.
It's fairly rare, but excessive yeast ingestion can cause yeast infection in some people, most often women.