Most of those options are overlapping and redundant though. Only the total range really matters, by simplifying the front the whole system becomes easier to use and mechanically less complicated.
Wear on the chain is greatly increased though on a 1x12 versus a 2x10, because of alignment.
Tolerances on a 1x setup are also much tighter, not ideal for long distance cycletrekking adventures.
Also, with a front derailer, dropping the chain to a smaller cog in the front to get to a lighter gear results in much happier shifting than having to lift the chain to a larger cog on the rear derailer when going uphill.
When MTB racing you can really get some advantage out of shifting combination discipline using a front derailer, when going from a downhill into an uphill.
I'm sad it's hard to find a 2x setup on new bicycles nowadays :-/
Tolerances on a 1x setup are also much tighter, not ideal for long distance cycletrekking adventures.
Also, with a front derailer, dropping the chain to a smaller cog in the front to get to a lighter gear results in much happier shifting than having to lift the chain to a larger cog on the rear derailer when going uphill.
When MTB racing you can really get some advantage out of shifting combination discipline using a front derailer, when going from a downhill into an uphill.
I'm sad it's hard to find a 2x setup on new bicycles nowadays :-/