This is of course true that YC provides this platform but, tapping in to my religious upbringing, it's a bit like confusing a church for the building it's in. Ycombinator owns the building that the community meets in, but the community is bigger than the landlord. The landlord can set some rules and influence what happens in the building, but if they impose too much on the community it will find a different building to meet in.
If you think that the values of a church have nothing to do with the discussions that happen inside of the church, I'm not sure what to tell you. If you believe the opposite, that's exactly the same point that I was just making.