The true statement is "We consumed this amount of power and were able to process this amount of transactions" but the power usage does not scale with transactions. You could increase the block size and get far more transactions without changing the power usage because the power is not used to process transactions.

> You could increase the block size

It's not that simple. As I recall the last time a block size change was proposed it fractured the entire community and produced a splinter "currency".

Its technically very simple but politically very difficult. The point I am making is that the power usage is not directly tied to transactions. Not making a transaction on the blockchain will not save X watts because that power is burned regardless of what transactions are going through.

An example would be that me not driving to the beach saves some fuel but bitcoin is just a train constantly driving to the beach and back regardless of how much I use it. You could grab the number of trips and the power usage and calculate a power usage per trip but its not an entirely useful metric since the power usage does not scale up as more people use the service.

The splinter fractured and has his own little splinter too now!

Without a backlog of high fee paying transactions, Bitcoin mining becomes unstable, as discussed at [1].

[1] https://bitcointalk.org/index.php?topic=5306354.0

Segregated Witness (SegWit) was activated in July 2017. https://en.wikipedia.org/wiki/SegWit And overlays like the Lightning network have been in use for even less time.