Where was the original violation that kicked in GPLv2 Section 4?

That wasn't the justification for creating GPLv3 at all. There was very clear reasons stated throughout the very large drafting process involving many members in the volunteer community and several vendors. There has been many good advantages as a end result. Apache v2 license compatibility, explicit patent license and internationalization among the large items and other several smaller ones include more explicit terms when recovering from a license violation, dealing with bittorrent distribution etc. GPLv3 *is* a better license.