This decision is enormous, enormous news for Cravath. They've probably done it like 3 times ever, and once was recently a BK guy from Skadden at the height of the crisis. That anonymous poster also meant partner-track laterals, i.e. mid-level and senior associates, which Cravath at least claims to not hire at all, rather than partner laterals (who they also claim to never hire). It's actually a point the firm tries to sell: the only way in is through the front door, they boast about not hiring laterals.
As for why that anon said (s)he wouldn't work for Cravath over most other V10s, I can provide some context. Cravath has a great reputation and interesting, professional people. But it also has a well deserved reputation for working its associates more consistently and in a more demanding fashion than basically every firm other than Wachtell. It likely at one point enjoyed a reputation that exceeded that of places like S&C, DPW, STB, Cleary, etc. but that's not true any more. It's probably not worse, but signing up to work there basically guarantees you longer hours. While there are going to be associates at every other V10 who pull hours longer than attorneys at Cravath, it's not quite as institutionalized.
And the point about mistakes during the crisis is pretty on point. A partner there has admitted as much to me in person. Cravath saw its PPP fall 24% or so in one year. Still a profitable firm, still a prestigious firm, still a place that will launch incredible careers and train talented lawyers: but there's almost nothing you can point to that would make it a better
choice than another V10ish NYC firm, unless you found it a particularly strong fit personality wise.