If Earth has pressure (like the deep Ocean) from gravity then what if you need to Decompress the Human Body in a Decompression Chamber to keep the body from fatigue?
The atmospheric pressure at sea level on Earth Caisson disease, and therefore in habitats on Mars, is 14.7psi, not anywhere close to deep ocean.
Since your post is regarding Mars Pressure Suits, there is no relevant analogy
Decompression form ocean depths is to prevent decompression sickness aka Caisson disease, resulting from nitrogen forming bubbles in a reduced pressure environment (the surface) after deep ocean dives, and is therefore irrelevant on Mars. Such decompression has nothing to do with fatigue.
STS used about 10psi, but Mars habitats could safely go to 7psi without any problems, as long as the partial pressure of oxygen was around the 20-25 kPa range.