I agree, it would be a ridiculous amount of work to start defining that some games are worth less than others.All the rating is ever going to do is predict how well a team is expected to do in their very next recorded game. Can you imagine trying to determine the relative value of each game programmatically, at scale, before deciding how highly to weight that particular game? What is a showcase game compared to a local tournament compared to a national final compared to a pre-season game? What about a late-season league game where everyone decent sits to keep them healthy for playoffs?
The rating is always going to be a calculation based on the past (up to) 20 recorded games in the past year. A game is a game if the score is published and the team can be identified. What some teams do, even at the ECNL level, is just have events with a whole bunch of friendlies and don't record the scores electronically. I can't imagine it's done specifically to avoid hurting anyone's SR score, but it is definitely an accompanying side effect.
The bigger question is why do leagues post showcase results if they dont apply to league status? Even if showcase results do apply as a part of league status why not keep the details internal and only post winner/loser not showing the number of goals scored.

