Nobody's stopping people from paying for answers... but I assume most of us are here because we have our own sites to administer and not because we're looking for paid work. Unfortunately for people looking for commercial solutions, I think that's the situation for most open source software. OS programmers believe in free exchange of information and tools, that's why we support such projects whole-heartedly and are happy to take the time to learn what we can and contribute what we can.
For those just looking for a product they can pay for and leave, I'd venture a guess that that sort of outlook is not so sought for in open source projects, but that might just be my own opinion. It seems fair to say open source software is more than just the product, it is a part of a larger philosophy of participation and exchange of ideas, tools and information - money is nice, but much nicer as a donation than as a salary, though I suppose that may seem idealistic by some standards.
Hope that's not too much of a rant, just some thoughts.