Why conduct Interview research and prep?

Candidates have two main components they are evaluating and making a decision on: Company and Role

1. Company - founders, investors, reputation, macro-culture, benefits, market presence, resources
2. Role - your boss(es), co-workers, peers, collab partners, resources, expectations (quota, territory, metrics), tools, communication methods and style, chemistry and management style, micro-culture, departmental dynamics.

Research the company - easy enough to do via internet tools.
Research the role/job - hard to do without engaging directly with individuals and leaders inside or recently inside the company.

Studies have shown that job satisfaction is weighted roughly 70/30 in favor of Role/Job.
Do I "enjoy my work", my boss, my team, my clients/prospects, my product or service?
Is my career accelerating, regardless of whether the company is or isn't?