Not going engage in a pissing contest over attendances but what you're saying is basically correct about team selection for these Carabao games - virtually every club does it. Even with the wholesale changes Warnock made for our game, there was a lack of footballing quality which is not surprising given that in general, our first choices lack that as well.
Back to the attendances and comparing them. A lot will depend upon the performances in the league games to date as to whether it becomes an attractive prospect to view. In your case, it's obvious - in our case I didn't go and I suspect many others like me also failed to show up due to our patchy (and that's being kind) league efforts recently.