I don't know which riders you were looking at, but straight doesn't necessarily mean locked. I ride pretty comfortably with my arms straight. As my elbows go from just straight to locked, the inside bend of them rotates from being slightly angled down toward inside to being on top. Doesn't matter whether on the hoods or drops. Not sure how to really describe that.

Nonetheless I'm not sure I'd assume that just because ones arms are straight that they are locked. I know a few people that locked elbows would be way past straight.