A chemical story?
Answer:
There are so many enzymes surrounded by the cell because there are numerous functions the cell perform. From mitosis to growth to the production of energy via ATP. Enzymes are biological catalysts. A catalyst is something that desires to be present before two or more substances can act in response with respectively other. It, in itself, is not destroyed or used up during the process. it is what you might hail as a chemical enabler. Only tiny amounts of enzymes are needed to aid the process.
BTW, Not Only Enzymes, Because they Are Catalysts.
I am sorry if my answer sounds a bit strange.
Nature is just the path it is. There is no "what for" or "why". It just happen to be that way.
In veracity, the question to ask is: what would crop up if it was surrounded by another way? What would arise if there be more or less, and whether the amount be very high-ranking?
If it proves to be lethal, consequently you have your answer: Natural test; pure Darwinism.