It has been for a long time. PageRank was never designed for adversarial scenarios. It reminds me of KPIs like lines of code - it's only useful if it cannot be manipulated. "When a measure becomes a target, it ceases to be a good measure." https://en.wikipedia.org/wiki/Goodhart%27s_law
That all seems pretty quaint these days, but even worms and viruses at the time were versions of "my goodness, who would ever write a script that emails itself to your address book, or copies itself across the network to all the other unsecured PCs with passwordless full hard drive access?"