Summary: think of the so-called 'soft freeze' as an extension of your refrigerator, not of your freezer.
The major things that happen to frozen foods that degrade their quality are:
- Expansion of ice crystals during warming and cooling cycles of the freezer, degrading the texture of the food item (making meats, for example, exude more juice or even appear weepy)
- Enzymatic or chemical changes over time. These are slowed more and more the colder the freeze.
- Fats become rancid due to interaction with oxygen, again slowed the colder the freeze
- Freezer burn, as water sublimates from the food, again exacerbated by warming and cooling cycles and the freezer, and proceeding more quickly at warmer temperatures
You will note that almost everything that degrades the quality of the food items proceeds faster at warmer temperatures (even when those relatively warmer temperatures are below freezing).
So, in general, the colder you can keep your freezer (within reasonable limits), the longer the quality life of the food products stored within it.
As reported by the University of Illinois Extension, food is safely stored at 0 F (-18 C). All (relevant, before someone points out cryophiles) bacteria are dormant at these temperatures. The University of Nevada Las Vegas indicates
Most foods will maintain good quality longer if the freezer
temperature is -10 to -20 °F. At temperatures between 0 and 32 °F, food
deteriorates more rapidly. Fluctuating temperatures, such as those in
self-defrosting freezers, also may damage food quality. Do not plan to
store frozen foods for the maximum suggested time if your freezing
unit cannot maintain zero degree temperatures.
The soft freeze temperature of 23 F / -5 C simply does not meet these standards, and is not useful for long term freezing.
So given all of this, what is the point of the soft-freeze feature of your new refrigerator? It is to allow you to keep food ready to use fairly quickly, as meats will not generally freeze completely solid at these borderline freezing temperatures, and are quicker to warm for preparation. It allows you to hold them for longer than you could at normal refrigerator temperatures, but not to store for the long term as in freezing to the recommended temperatures.
This is in line with the information given by Samsung:
The Soft-Freeze temperature helps keep meats or fish fresh longer.
