If something is known to be used as a proxy for quality and people are rewarded accordingly, then you'll end up with people trying to achieve the proxy for quality at the expense of actual quality.

But isn't that exactly what happens in science too? Citation stat gaming, ghostwritten papers, senior person's name first, etc.?

And those kinds of gaming are much harder for outsiders to detect, as well as harder to fix or regulate, especially when they're the commonly accepted official practices.

So even if the public data aggregation approach is more open to gaming, it doesn't necessarily follow that it's more vulnerable to gaming. Gaming might also be much easier to detect and/or eliminate by automated or semi-automated means.