Indeed, AF is beneficial in some landscape scenarios (Especially for cameras with limited or no live view capabilities, such as CCD backs), but the "lack of accuracy of phase detection systems making them unsuitable for landscapes" statement is laughable. There are very, very few situations in landscaping where a razor sharp focal point confirmation is needed. One is mostly working with zones of focus and it doesn't make any noticable difference if the actual plane of focus is a wee bit ahead or behind the intended plane of focus, at working apertures for landscapes.
I have used Phase detection AF for landscaping on multiple formats and have made 40"+ prints and have never once thought "Dang, this PDAF thing is totally unsuitable for landscaping"!
In fact, if one knows how to do AF microadjust, I don't even see how PDAF is a limitation even in shallow DoF portraiture.
This sort of pedantic complaining is great for the Diglloyd types, but it is hardly a limiting factor for anyone who is doing real work. Sure, CDAF/ on sensor PDAF is more accurate and there is no need to fine tune it like one does with mirror based systems, but people have been doing perfectly good work before those two came along.
Regarding the speed of Canon lenses on the A7RII, I don't have any first hand info, but from what I see here, it is perfectly usable.
https://www.youtube.com/watch?v=6yottoM_P1oNot as fast as on the Canons obviously, but definitely usable in the field.