As far as I can tell, there is a disincentive to have a runner deck that concentrates too much on virus counters. The corp purges all virus counters for a fixed cost, though that cost is significant. However, the more the runner concentrates on getting virus counters, the move value the corp gets for that fixed cost. There doesn't seem to be enough synergy encouraging specializing in virus counters to justify it, is there?
That is, it seems you get the most effect for just having 1, maybe 2 virus counter-related tricks. After that, it's diminishing returns.
And, yes, the corp can still win, even when skipping one out of every 2 or 3 turns to purge virus counters. This is when the runner deck relies too much on virus counters such that it can't function without them and needs more than 3 turns to build back up again. Even worse when the runner spends resources and the corp only spends actions.
Is there much incentive to specialize rather than dabble? Anything other than the original Anarch identity card?