Filler in marionette folds - pointless?

Thanks for the question.
Unfortunately it is hard to comment without seeing a photo of yourself. 
As you say, marionette lines are due to the loss of volume higher in the face leading to sagging and the deepening of this fold. Ideally this should be treated by a combination of adding volume higher in the cheek and a skin tightening procedure. 
Adding volume (filler) directly to marionette lines can mask them and is quick, easy and relatively cheap and so I do this at some patients request but it needs to be down with respect for your facial shape. 
Your plastic surgeon should be able to discuss all the options of direct fillers, a filler based lift, skin tightening (Ultherapy etc.), thread lifts and face lifts to name a few and discuss the pros and cons of all of these.
Good luck.
Dr Chris Macdonald

Normally I do not start with the marionette lines as you describe. I typically augment the cheeks as needed, fill perioral lines and lips, then consider marionette lines. Using other modalities such as Botox, laser, etc to help achieve your specific goals. Go to someone who will discuss your concerns and come up with a multiple modality plan as needed to address them. 

Dermal fillers are commonly used to correct Marionette lines. They are also commonly used to correct volume loss from cheeks. Would really need to see good photo's for opinion on your situation.

Hi
Without seeing a picture this would be hard to comment but typically filling this area is one of the more aesthetically rewarding treatments because it is a very clear issue.  Everyone has Nasolabial folds it is a question of degree.  We do not have Marionette lines until we  age.  So their appearance is something that we at one time did not associate with our “look”.
Your doctor should be able to go slowly and you will see how it looks initially and will be able to choose how to move forward 
Good luck

It is difficult to evaluate a person without an examination but you are definitely thinking through this the right way. As we age, we lose volume which creates sagging and the nasolabial folds as well as marionettes get deeper. By lifting at the cheeks, you will have a more natural look and hopefully use less product in the lower face. For full correction though, keep in mind that you may need 4 (or more syringes). Again, cannot tell you exactly how much you will need without actually examining you in person but based on my 10 years of experience, most patients need a Voluma in each cheek, a syringe or 2 of Vollure or Ultra plus in the marionettes (and/or nasilabial folds) AND don't forget the lips which decrease in size as we age as well. I call the lips "the icing on the cake", you need to PLUMP the lips (soft enhancement) to finish the look. Go to an injector with a lot of experience and he/she will be able to on guide you on your needs. I would stay away from only injecting  the marionettes unless you truly only need minimal correction. Good luck!

Thank you for your question. It is difficult to adequately address your question without a proper exam or baseline photos. I advise posting a few clear photos to allow for better assessment. Generally speaking dermal fillers are best used to achieve balance and symmetry of facial volume so your concern about relative overfilling of the Marionette areas is valid. However, combination of different fillers may be used for pan-facial volume regeneration. It might be worth seeking a second opinion from an expert physician. Good luck! 

Impossible to comment on without a realtime examination with touch. A good injector will know where to fill to give you the best outcome. Most Specialist will look at the source of the problem, and not where the lines are. By volume displacement, your lines will look less deep, but also you will have a natural and enhanced look- this is the trust that you should have with your Specialist. If you are in doubt, seek a second option from an aesthetic dermatologist, or plastics. All the best, Dr Davin S. Lim. Brisbane. Australia.