Even though I have a different opinion, I understand your opinion quite well. Your motivation is quite sensible, but in this case many matches countries as i.e. Sweden, Poland and Germany have played, should be deleted as these countries played two (Sweden even on one occasion three) matches simultaneously. The double fixtures mostly have one thing in common. The real A-team played against serious opposition, the other one (actually B-team) against weak opposition.
The latter is also one of the reasons I even would count matches B-teams played against Luxembourg as A for both sides as we can read here. It even happened regularly the B-team obtained at the time better results against Luxembourg than the A-teams, especially in friendlies. In most NT's about four or five players are very sure it won't cost their place into their NT if they play poor in a friendly against Luxembourg. Those who take over their places will give 100% in order to show te coch hey should play. They are more motivated than the regulars.
The Croatia case vs Mexico is different, but it still is a match a coach can test new players. Indeed, this way you devaluate A-international matches. Nevertheless, history has shown a lot of such matches. Around 2010 it were the August friendlies, but since then - and even before - also the many subtstitutions in friendlies which even have killed many matches.