You are correct, anyone has the potential to earn rewards at a reasonable level, but it does seem to be those who invested real money that are now whales and have huge earning potential, some may say an unfair advantage...but those whales quite rightly can expect a return for their investment of real money which is in many cases 10s or more of $ into STEEM and powering up increasing there ROI even more...is that unfair, NO.
About the bots, the bot population seems to be exploding more and more every day, you are correct in that many are good bots..although operated as a business, and a business main aim is to make a profit. Why are so many of these bots using an auction bidding process instead of flat rates...profit pure and simple. Is it wrong some say yes many say no (by using the services offered in their search for more rewards/money.
Even what many consider miniscule rewards can make a huge difference in a persons life depending upon their geographical location, this is a great thing about Steemit, it is socmed that truly gives back, the focus on money is hower=ver wrong and will backfire badly for Steemit when bad word of mouth spreads if users are not earning. People pissed off with the platfrom will tell many more about that than those happy with it. It is a marketing fact that people who believe they have been "taken" will talk a lot more than happy users.
There is randowhale that has flat rates and most followers, but yeah, each user has the freedom to use which bot they like, in the end supply for the bad or unfair ones will die off.