Sure, but let’s say you have versions A, B and C of the same typeface, which are achieved by replacing some glyphs and features on export. Now you need to maintain a duplicate of the same instances for each version (differing by parameters/family names), and remember to activate/deactivate them for variable exports. Alternatively, you can keep one set of instances and manually replace the names/parameters before each export.
Meanwhile, all that is already solved for variable — 1 set of instances and different variable exports for each version. Same for static…? 