You're almost right.
Change is to can be and I'll meet you half way and agree.
The thing is that selling in public lobbies, while not impossible as you proved, can be toxic and is still unbalanced and unfair. These aren't whining or incorrect facts, these are rightful complaints and true facts.
However, the complaint I have, which spurred this whole thing again, is the constant whining about it being impossible and toxic and nothing else. While an issue, it's not as big an issue as it is being made out to be and there are plenty of ways to avoid it (including solo public if needs must but, as exampled, are not required).
Selling in public lobbies can be unbalanced, toxic and unfair.
Well, maybe people complain way too much because they don't like how the whole system is setup since the Further Adventures in Finance and Felony Update.
Maybe people hope that if they speak their voice, maybe R* will revisit the concept and improve instead of only copypasting it each update.
And while recent updates have improved the concept (Gunrunning had supplies being able to be lifted with the Cargobob and a generous countdown to initiate the global signal; Smugglers Run let players steal cargo from others, which is way more profitable and makes more sense that just destroying it), there's a long way left to improve it even more.