You don’t understand how important online buzz is when it comes to attracting new customers. Why do you think romance mangas push debates about who the protagonist will choose.
Oda cares quite a bit about whether his manga is being talked about
Even if nakama stuff affected sales, there's plenty of stuff he could tease that will actually happen. Most people are more interested in void century stuff, laugh tale teases, or joy boy lore. What's the point of teasing stuff just to say "nevermind" and not do anything with it?
Also, romance mangas do that to keep the end result a surprise. They're not invested in what reddit talks about.