There is a huge difference between Loeffler and Burr. Loeffler is married to the chairman of the NYSE and is having her portfolio managed by people who have as much and maybe more information than Congress does. She also has so much money she dumped everything just to avoid the aggravation. Burr had nothing but what he knew from hearings and the stocks made up the majority of net worth.
I get your point about Loeffler but in government there is generally an obligation to avoid the appearance of a conflict of interest because it can be perceived as impartiality, if not worse.
The whole COI thing gets quite complicated among the three branches of government, but with respect to Loeffler she evidently was not the least bit concerned about the appearance of COI.
I have personally recused myself from situations that had even a remote potential to call into question my impartiality.