I disagree there, just because a unit happens to be effective against a few targets, does not mean its not a hard counter to some of them.
Good example is the scout car, this unit is the hard counter to snipers, but it is also useful against most forms of infantry, and even light vehicles. That does not mean its not a hard counter to snipers.
Another is any medium tank, which will be a hard counter to light vehicles, does not mean its also not useful against other vehicles and infantry...
I see where you are coming from. The scout car is the hard counter to the sniper because its the most cost effective option for dealing effectively with snipers. While the scout car is also good against light vehicles it still isn't the hard counter to them because there are other more cost effective ways with dealing with light vehicles. A hard counter is the most cost effective unit for a specific role. While medium tanks are a very effective soft counter to light vehicles, it is not the most cost effective option. Mines are the most cost effective way of dealing with light vehicles because they were made for that. Its easy to get effective soft counters mixed up with hard counters.
An example of this would be the ISU 152. You can't say the ISU 152 is the hard counter to everything just because its very good at dealing with everything. This is because it costs so much and is out performed by other units RELATIVE to its cost. You don't buy an ISU 152 to deal with scout cars. You buy an ISU because it CAN deal with scout cars and many other things. The key here is cost relative to performance in a specific role.