Not for all languages
I estimate 15% of my Python golfs with list input could be shortened by taking in its length, if that were allowed. Hundreds of golfs in mainstream languages could be improved by mechanically replacing "
len(l)" or similar with an input parameter.
These submissions strongly suggest that golfers wouldn't guess this to be allowed without knowing the rule specifically. This is a hidden rule of the worst kind -- broadly useful, unexpected, and likely to make golfs more boring on average.
I'm sympathetic to the problems languages like C have with cumbersome input processing, especially as they already have many disadvantages. Golfing languages can be designed around such issues, but C is stuck with them.
But, I want to avoid the trend of giving all languages an easy extra workaround because one language really wants it. The result is a laundry list of liberties with input that go beyond taking it conveniently and naturally for the language, to doing parts of the golfing task in the input format, justified by citing obscure meta threads about other languages.
I'd rather say that this is a property of C that golfers need to deal with, or that a C-specific rule be made. Either one would be better than changing the rules for all languages.