That wasn’t my point, and was why I originally said that you and Sharlin seemed to be talking past each other.
LCDs took off because of their physical advantages (weight/thickness/heat, although the heat it produces has to be correlated with energy input) despite their shortcomings (fixed resolution, limited brightness and contrast ratio, response time) and plasma screens were an attempt to deal with those shortcomings but are now mostly dead. As you say, improved efficiency was correlative but not entirely causative.
A naive view would have been that as LCDs took off, their efficiency would lead to a drop in power consumption over CRTs. The Jevins paradox shows that not necessarily to be the case - bourne out by the proliferation of displays where previously there were none and in displays getting larger.