Of course obesity worsens these and other health conditions, but it doesn't follow that it causes these conditions and it doesn't explain the many skinny people who suffer from these conditions too.
Many obese people also don't have heart disease or osteoarthritis, so by your logic obesity doesn't "cause" those things either, or anything. It's all about the bowl of beef fat chunks!
There's also no way you read anything I posted up there so quickly, again you're just interested in reinforcing your bias. There's plenty of compelling evidence that obesity plays a causal role in these things.