Perhaps because there's more to a camera than just the sensor alone? IIRC the main reasons for panning the earlier Sigma cameras had a lot to do with their ergonomics and responsiveness as picture taking machines and not much to do with the sensor performance.
|Street Food by poppyjk|
from Your City - Local Street Vendor
|Tomato Clownfish by chile7236|
from Fish world
|Vermont-Autumn by kevinplui|
from My Best Photo of the Week