I will attempt to address this from the multitude of facets - as this is complex just as our divine Feminine bodies are.
These are my observations, teachings etc from over 25 years working with Ob/Gyn's, being a doula, healer, as a Priestess and a Feminine Embodiment Educator and Alchemist
The First area to look at is Physical: Vaginal weightlifting is a relatively new practice (under 30 years last I researched) with no proven benefit that exceeds regular kegels, beyond the sensationalism of being able to lift large objects using only the vaginal muscles. The current concern facing many many women is hypertonus (Thanks to years of being told to do kegels incorrectly)- in addition to the subtle bearing down that many women experience during exercises, emotional distress, wearing waist trainers, after hysterectomy etc;
These two very different and yet connected concerns seem to contraindicate the use of Vaginal weightlifting as being helpful. Embracing practices that focus more on isolations of the various muscles in the pelvic bowl- including a squeeze and release- is more beneficial.
You can find wonderful practices in my Book - Yoni Egg Secrets available on Amazon HERE (If you do not have a Kindle you can download the app FREE)
Energetic - The Yoni is not created to lift weights. There are no circumstances naturally occurring in which these muscles would be used in this way. The furtherance of a belief that one of the most sacred aspects of her Feminine expresses strength by lifting proportionately HEAVY items adds to the limiting belief that is present in the Feminine Energy body that women should equate strength with weight. This belief doesn't ultimately serve women.
Believing that we need to express strength in a Masculine way by our ability to lift heavy burdens tends to eventually lead to burnout, depletion and exhaustion - which is rampant in western culture. Harder isn't always more beneficial, More isn't always better.
In Laughter, Love and Lusciousness,
~Namaste