Just a rant incoming.
Their reasoning has less to do with reaction time and more to do with consistency.
i.e no amount of latency will matter as long as your shots register the majority of time... they also don't talk about the interpolation delay caused by the low tickrate... hell, majority of people do not even know what this is or what interpolation does.
20hz is enough to get a good enough packet flow for clients to interpolate and for the server to do proper rollback (upping to 60hz and causing bufferbloat f***s with hit registration as you get delayed packets, or outright dropped packets).
But we get a ton of "issues" with delayed response times because we need at least 2-3 snapshots/packets to properly interpolate (meaning minimum 150ms inherit delay on top of your actual ping).
There are some other things that needs to be mentioned with 60hz servers, which have less to do with servers being able to handle them and more to do wi...