Some simply do not absorb transdermals, of any sort.
Some do for a while then the door slams shut. Skin changes some how.
Transdermals create more E than injections. This is a problem for some.
Those who have hypothyroidism are famous for not absorbing T transdermals. One could consider not been a transdermal absorber as a symptom of hypothyroidism. Most docs have no idea and want to increase the dose.
When one does not respond to a transdermal, doubling the dose often does nothing.
If transdermals are not working, you need to inject.
Transdermals are much costlier than injected T.
For those who train or work where they sweat a lot and or showering, this can make transdermals inappropriate.