A league I'm in has a very similar scoring structure. The difference is -3 for a loss. While people still scour for 2 start pitchers there are a very limited number of 2 start pitchers who are already available and have favorable matchups. In many cases starting a stud pitcher will still outscore the 2 start scrub.
Consider with my scoring:
Stud pitcher goes 7 INN, 5 Ks, about 8 hits/walks, 3 ER and a W. Score: 22 pts.
Scrub goes in two games: 12 INN, 7 Ks, about 16 hits/walks, 7 ER and one W, one L. Score: 23 pts.
if the case happens where he gets dinged up once and goes fewer innings, gets no-decisions or worse gets 2 Ls you can quickly get into the single digit or even minus points. The stud pitcher will likely still net you 10 points even if he has an off day.
Of course the scrub could also go: 14 INN, 8 Ks, 16 h/w, 6 ER and 2 Ws to get 42 points but I would say the liklihood that this guy isn't already scooped up is low. Plus the swing is too great to have a consistently winning team. Yeah, you might break the bank a couple times but the risk of doing this with your entire starting pitcher lineup is low.
It's much more of a risk when the negative points are added.