Help with bounty on an answer

Question

I wanted to reward a bounty for this answer. Intent was to reward 50 of my rep, but the minimum I could reward was 100 (it's a first time bounty on that question, so subsequent bounty clause doesn't apply)

Little research showed the reason- because I had also answered there (for questions I had not answered, I can award 50 as minimum, just as I can do for my own questions)

That is fine by me and I went ahead and placed 100 bounty as that particular answer was very useful to me

Questions

• I do not see any documentation on the site or on meta saying , saying "if you want to award a bounty to an answer, where you have also answered, the minimum bounty is 100 "

• What is the logic behind this? ( I fail to see how the person who is awarding his rep needs to part with more of his rep, just because he too answered the same question)

Edit: Thanks to Andrew (again !) for providing clarification. That said, I request that suitable amendment be made to bounty help page, so that it is clarified once for all without reference to meta (in future)

Answer 1

This rule was added due to a discussion on Clever bounty reputation hack (on Meta SE) back in 2010.

So here's the hack:

1. Find an interesting question
2. Research and provide a very good answer
3. Open up a bounty on that question to attract attention and votes to your new answer
4. Profit!!!

2 and 3 may be out of order--I didn't see the timing of it. But either way, assuming he gets more reps than the reps spent for bounty, he still gets increased rep out of the deal.

[...] it does generate some useful discussion and insightful answers. Plus you can increase your own rep very rapidly by making your answers highly visible, and therefore frequently voted upon.

In which, it was responded by an ex-SE developer,

Note: we added a few more checks and balances

• If you are placing a bounty on a question you answered, your minimum spend is 100
• If you are placing a repeat bounty on a question, your minimum spend doubles till it reaches 500

^{(Emphasis added)}

From this discussion, I assume it's to prevent "infinite" rep gain from increased publicity due to a bounty (especially, the doubling, but it's unrelated to this case).