My wife’s very recent PhD experience at Oxford was a little crunch time around conferences, a nice 20/25 hour week, and enough spare time to row with the Oxford Uni boat team. She stayed a year as a postdoc and it was much the same. She’s now a postdoc at Stanford and she’s working 16 hour days, weekends, and very stressed for it. Academic output is the same - it’s just different work culture. I know this is about PhD students but I imagine it’s no easier for them than early career postdocs, so this seems to make a lot of sense.
Stanford is notorious for "duck syndrome". People are calm on the surface but are always paddling below the water. I would say the CS papers out of Stanford tend to be nicer than the ones out of Oxford though, at least for Systems research. (This is a huge generalization: I don't read every paper and there's enough variation between authors that it doesn't really make sense to do a cross-institution comparison, but this is only my half-formed intuition).
I think it's going to be very lab specific there, but you could be right for systems research (I've not read any myself)!. FWIW, she's in medical engineering.
Edit: All it takes is one tenured professor who strongly filters submissions for good papers to keep standards high for a department to look much better, but then you'd be stopping your lab from playing the citations/publications game which is necessary for future postdocs. I may be cynical.
