Yes. Up to and including V5, our approach was to write Rhino display code to a “least common denominator” OpenGL specification. This approach worked pretty well for many years.
With V6, we found some of the features we wanted to do, partly because of AMD’s Radeon driver group being so intransigent with respect to OpenGL, and other driver groups apparently were not adequately testing their reverse compatibility to older OpenGL specifications, the developers came up with a scheme that looks for OpenGL 3.3 and falls back to earlier specifications when an old driver or marginal card is encountered. It’s been a lot of work and we’re not done yet.
In my previous post, my use of “requires” and “will use” were specific.