“Why the emphasis on Iowa caucus?”
Only because it is the first one to give us some real data, instead of polls made with phone calls. Historically, some candidates who do absolutely poorly in Iowa, tend to drop out. New Hampshire isn’t vital and candidates tend to NOT drop out after that state. The big fall out happens after South Carolina.
I get your point. Doing poorly in Iowa is not so good. But winning Iowa seems to be a kiss of death in past 2 cycles.