If I can speak for myself here, I'll tell you my reasons. The first was this:
How can I measure back-EMF to infer the speed of a DC motor?
I read something that reminded me that I knew this, but it basically isn't documented on the internet. If there are search terms that will retrieve this information, I haven't found them.
How can I implement regenerative braking of a DC motor?
Why should I worry about a motor causing my supply voltage to shoot up when the back-EMF can't exceed the supply voltage?
are the result of a discussion about this one:
Limiting torque on a DC motor
Through that discussion, and other questions I read as research, it seemed to me that there was a feeling in the community that regenerative braking was somehow not present in ordinary motor drive circuits, and that you had to do something special to get it. I know this to not be true from personal experience, after blowing out a few dozen motor controllers until I discovered what was happening while designing one for a small electric vehicle.
I don't feel the slightest bit guilty about the reputation I've received from these. It's not as if the reputation I gain comes at the cost to someone else. I put a lot of time into drawing those schematics, proofreading, editing, researching, and verifying them. For all three of those together, the answers have received 24 upvotes. Not exactly a steal.
How can I efficiently drive an LED?
I wrote this one because there were hundreds of answers like, "Ugh...I'm not going to explain how to calculate the needed resistor again and no, you can't put them in parallel." but really none that took the next step and explained other ways to drive an LED. It's not uncommon for someone to ask about driving a lot of high-power LEDs, and although they are asking about resistors, the answer should really be, "You know, resistors will eat up 1/3 of your battery. You should look at some more efficient methods." I guess when there is some variation of this question every day, it's hard to take the time to write a good answer for each one. I wanted a canonical answer to link to.
If upvotes are any indication, this mundane answer was the most appreciated. It has now 36 upvotes, more than the other three combined. Ironic, since it contained the least interesting information. Still, I don't feel guilty. It filled a real need on the site. It addresses a very popular problem. I must have spent two hours on that answer, drawing the schematics, making the graphs, making sure the language was easy to understand and accurate.
In my opinion, more people should be answering their own questions. If you learn something that is useful but was hard to find, make it easier for the next person. You also give your research a chance to be reviewed by others, to make sure it's correct. This may not be pushing the edge of science, but it is advancing the boundary between accessible and arcane, which is just as good.
This behavior is encouraged by the design of the site, by the "answer your own question" link at the bottom of the "ask a question" page. People won't game the system by flooding the site with useless information. This wouldn't get any upvotes, and it would attract the attention of moderators if it got bad enough.