Dave Burke discussed the choice to not use OIS at the Nexus launch and stated it's using the same Sony sensor for digital stabilization as the ones used in Sony's dedicated cameras, eliminating the need for OIS. So far you've just heard from DXO who so far has ranked 2 of the 3 top phones not having OIS, A senior Google Android engineering executive, and Sony who makes the sensor used in the Nexus 6p as well as Sony cameras.
There's your facts. I don't know what more I can offer you without getting the feeling you're just clinging to OIS and are unwilling to acknowledge sensor tech has improved now to the point that it's no longer clearly better. Maybe you were previously unaware of the advances recently made? Hopefully you are better informed now.
Ok. So give me a list of who you are waiting to hear from with respect to the Z5 camera and I will be the first to post their opinion of it here and we will see how far it varies from DXO assessment. Deal?