This is just patently not true.
I looked at the code for ClassicLFG, and it only calls SendWho() in one place (in a situation where someone whispers a group leader - it calls SendWho() on them to get info on the person).
Meanwhile, CensusPlusClassic’s entire existence is using SendWho() to gather character data…
My guess is it was done to alleviate server load - especially as more and more people were running the addon, doing /who calls basically constantly. (More on my thoughts in this thread: Breaking CensusPlusClassic (making SendWho() protected) ).
There were a few other addons that took collateral damage from this, unfortunately.
Given Blizzard has never had issues w/ the Census addon (which has existed for 15 years in one form or another), I’d like to hope/expect it is allowed back at some point - unless Blizzard would prefer to publish their own census data (updated regularly) instead…