Why are most people using huge hero-graphics (495kb?!) for short blog postings nowadays? On topic: Testing gets worse if the codebase which needs to be tested

Why are most people using huge hero-graphics (495kb?!) for short blog postings nowadays? On topic: Testing gets worse if the codebase which needs to be tested is garbage. My experience with other developers who learn testing don't need to learn how testing works - they need to learn basic development rules: Components, loose coupling, dependency injection, ...