alt Hacker NewsGrigori Perelman's papers were considered promising mostly because they were written by Perelman. When there are too many papers to read, the reputation of the authors becomes the most important signal of quality. Formal peer review tries to spread the attention a bit more evenly, but it doesn't scale too well.
On the one hand yes, Perelman was known within his subfield. On the other hand, I find it hard to believe that if some random person had published the same papers, they would have gone unnoticed, since as far as I understand it these were important results that would have been worth evaluating based on the titles and the abstracts.
Volume isn't really a problem going forward, at least in mathematics, since every proof can be accompanied by a Lean verification. Whether other disciplines can implement automated verification or quality assessment will depend on the details of the field.