This makes it sound like Reputation is just a glorified "badge" to mark how many liked posts you made from people with wealth behind their names.

That is exactly what it is. It is the grand sum of all the upvotes you've received times their weights. That is also how your rewards are calculated, so your Reputation is proportional to the amount of STEEM you've earned from posting rewards.

It doesn't have anything to do with how much STEEM you hold or how you vote for others. It also doesn't have anything to do with how many follower's you have or who you follow.