These online support techs are just reading off cue cards. It would be nice if they had actual experienced techs online but from my experience most don't.
I use SAE15W50 Syn over SAE20W50 Dino oil here in all hydrostatic oil change except when SAE10W40 is spec'd. So no you are not twisted to better oils. Now thicker oils do help on older units with lots of wear but once there unit start giving problems the only real way to fix them is to replace the internal pumps and center section. This is because most of us don't a machine shop that do the rebuilds with newly machined parts and shims.
These techs can't even tell you if the oil leak tracer dye are usable in these units which it is.