Guys the breaking strength of the line and it's thickness are totally different things. You can have 8 lbs line as thick as your finger, or you can have 8 lbs line thinner than a strand of human hair. It all depends on how the company engineered the line. The parameters are determined by the company.

Case and point: Fly fishermen use a variety of tippets of varying thicknesses and breaking strengths. That's why they have the X system in addition to the line thickness and breaking strength. There are far more factors than the breaking strength.

Best video on this explained via RIO: