Our OSMC skin doesn’t offer a scrollbar in the guide view. It just doesn’t make much sense to scroll all the way to the last EPG events available (to the right) to get to a scrollbar. If a scrollbar is visible, users will expect to get there easily. The guide view uses all four directions for navigation withing the EPG grid already. I can see that Estuary does this differently, but I don’t see a point in adding a scrollbar, if it could take up to 20 seconds to get to it… 
EDIT, see my post below.
@JimKnopf’s screenshots show very nicely what we’ve already added to the v18 skin to make navigation buttons clearer. The guide is different to all other views. We don’t work on the v17 skin anymore, so you’ll be able to benefit from these changes once our v18 stable release is out or by switching to our v18 nightlies: [TESTING] Kodi 18 (Leia) builds for Raspberry Pi