Some community-oriented/UGC startups nowadays seem to prefer modest growth, at least for a while, to make sure the right standards/user-expectations can be main

Some community-oriented/UGC startups nowadays seem to prefer modest growth, at least for a while, to make sure the right standards/user-expectations can be maintained. (Hypergrowth can mean a change in community makeup faster than desireable norms can be maintained, which can spoil the dynamics in a way that's hard to un-spoil.) Compare HN's own revealed preference for limiting certain surges of new users. (Corollary: HN is not a 'startup'.) In a way, even Facebook's initial campus limitations served this purpose, getting certain mechanics (and corporate practices right) before facing the challenges of a larger userbase. I wonder: have YC companies had to face an explicit decision: grow faster or defend/consolidate the culture of the existing userbase, and if so what advice would PG and the other partners be likely to give?