Starcraft's Campaign AI doesn't rush you ever. Nor does the Campaign AI group up or mass up their units. So even singular ships (ie: single Battlecruisers) can make surprising progress.
Those players then come into multiplayer mode and get wrecked by the multiplayer AI or humans of course. But that doesn't change the fact that I've met these people (ie: my more casual friends who thought they were hot stuff in Starcraft back in the day).
Right, it's not completely impossible, but still requires a ridiculously specific set of circumstances...
And while controlling a single hero unit might work in the campaign scenarios featuring them (and not even all, good luck dealing with air units even as a hero firebat !),
it's not going to work if you for instance decide to leave to your military buildings and units alone the job of winning the mission while only do resource production !
Those players then come into multiplayer mode and get wrecked by the multiplayer AI or humans of course. But that doesn't change the fact that I've met these people (ie: my more casual friends who thought they were hot stuff in Starcraft back in the day).