For a very long time the alliance score was the main factor in the match making, so a lot of alliances/players got into the habit of using it as a basis for comparison. Some alliances/players never did see the updated information and are usually surprised to realise it’s been changed.
I agree there should be a better way to make this information prominent. In the meantime, it’s become the responsibility of the forum community to help alliances/players understand the new match making system.
Hopefully it can be done respectfully. There is no point beating a person up just because they are acting on old information.