Compared with leaving the rival tribal factions to fight each other with ancient rifles, whether over education policies or just because they are rival tribes.

Seems you just forgot that the US hadn't left the rival factions to fight it out. Had it done so, the SU might not have invaded and the regime might have survived and implemented the more enlightened policies. The people might have been spared the Taliban and the subsequent war - and the recent return of the Taliban to power in some areas - where they continue the oppression of women - amongst other things.

  The Soviet Union never provided effective aid to to Latin American liberation movements and progressive governments regarding Latin America to be within the American Sphere of influence.

Of course they did help Cuba - a far better regime in general than  the typical dictatorship the US had no problem supporting for all the rhetoric about freedom and democracy. That nearly precipitated WWIII, so it's not surprising the SU  didn't help other liberation movements. Of course this didn't stop the US from lying about it - as in the supposed Soviet migs to Nicaragua, an invention which got on western media front pages. The later correction (if given) buried deep inside.

 The US was suppose to recognise Afghanistan as being within he Soviet sphere of influence - according to the cold war rulebook.  The US never attempted to invade Afghanistan directly in recognition of this principle.  That is why their actions there had to be covert.

In other words they ignored the principle by what they actually did, and the means were chosen in order to hide what they were doing from their own citizens - how very principled.

Maybe it's because I'm a Londoner - that I moved to Nice.