yeahbut if there was one task they could use them for but another for which the machines would be inutile, it would be more accurately nuanced to say "the teachers could not utilise the computers for the second task..."

In other words, the difference for me is the suggestion of fitness for purpose, whereas use merely says something about an action undertaken or not. I know what you mean about some of the over-usage, but I think it can yield a useful extra level of utility compared with the mundane use ;)