The comparison to a keeper in football is close, but in hockey it's a far more important and specialized role. In the NHL, a typical # of shots on goal is 30-35 [1]. Seems like 3-7 is a typical number of saves a football keeper would have to make [2].
Also, the equipment a hockey goalie uses is specialized, whereas I think the only extra equipment a keeper has is a different coloured jersey and gloves.
You are correct, football keepers make a much lower amount of saves - but goals tend to be fewer and hence "heavier" in football, so having a bad keeper will still likely result in a loss. And it's still the sort of role no regular player wants to do - which results in some funny differences at the cultural level.
At the very least, I guess this concept could work as a feature for all those apps people use to arrange 5-a-sides.
At the very least, I guess this concept could work as a feature for all those apps people use to arrange 5-a-sides.