I agree with you, STARTTLS Everywhere is not "a problem". It is not a solution either - at best a minor improvement.

The problem is not the MTA who will chose to be listed, but those who won't be listed - the immense majority. "Scalability limitation" is certainly a more polite way to say that.

I'm sorry if my message was too blunt, but I am not sure it was worth downvoting my technical explanation just for this.