well i guys i will explain again, we are talking about minimum requirements (minimum means the least requirements and its a latin word).
read this
135.245 Second in command qualifications.
(a) Except as provided in paragraph (b), no certificate holder may use any person, nor may any person serve, as second in command of an aircraft unless that person holds at least a commercial pilot certificate with appropriate category and class ratings and an instrument rating. For flight under IFR, that person must meet the recent instrument experience requirements of part 61 of this chapter.
(b) A second in command of a helicopter operated under VFR, other than over-the-top, must have at least a commercial pilot certificate with an appropriate aircraft category and class rating.
SIC means that you can be as per discretion of the PIC the PF (pilot flying) and the PIC could be the PM (pilot monitoring, as a matter of fact the PNF is going to disappear soon).
if it wasnt in this way how can a pilot build experience?
(dont tell me only CFI because thats not really the experience we are talking about)