Seems to me that unless there are actual forum rules about what rep can and cannot be given for (and if such rules do exist, then I've certainly never seen them written down anywhere), then people should be able to give rep to whomever they want for whatever reason they want.
Which they can.
The discussion here pertains to how people perceive and value reputation. That discussion takes place no matter the quantification method that's presented in society or smaller social groups (communities like these), be it karma, upvotes or actual monetary payment. Why does it occur? Because it's up to the people to decide how much it's worth and what it's socially acceptable to use it for.
Most often, and such is the case here as well, people don't enjoy seeing quantification systems being used for personal gain and glory (circlejerks or do-me-a-favour-for-rep), so this discussion takes place to encourage people to use the system in such a way that it benefits everyone as well as their own sense of justice and fair exchange (contributing to the community through producing content or thanking people for real help and/or advice).
Posts and threads that are not removed by me or other moderators contribute to the community since they are acceptable content, and as such provide a very small amount of reputation. Looking at your profile, you've gotten +rep from four different users for reasons ranging from making an appreciated joke to assisting in the facilitation of discussion. Apparently they think you've contributed to the community, and I'd agree. It is by
far the most common reason people give out rep.
Whether you agree with them and me is a different matter. If they gave you rep because of a reason, that is the given reason for the given rep. Your assessment of their opinion on that doesn't change the given reason. They're the ones who decide their own intention.