How to access the full capacity of hard drives larger than 2TB with OS X Yosemite?
The only conclusion I can draw at this moment is that OS X Yosemite does not support hard drives larger than 2TB.


Very wrong. Yosemite supports drives up to 8EB (exabytes. Or 8 million terabytes. You could download the internet with some room left over).

What it has problems with is proprietary file formats from other companies, esp. if the patent holder doesn't want to share.

If you want to access the full drive on your Mac, repartition it in Disk Utility and format as HFS+. If you want to share the data on this very large volume across platforms, the easiest way is a NAS enclosure (Network Attached Storage - basically an external drive with an ethernet port). The disk format only matters to the device it's directly connected to.