One might wonder why we don’t sell adverts in order to keep the service running. The sad fact is that the income that comes from the adverts is light years away from covering the costs. Another thing is that having ads everywhere wouldn't make the service pleasant to use.
The same goes with t-shirts and hoodies. There is just no way that 27 Crags would be able to run with selling t-shirts. Also we believe that we should be focusing on developing the service, not selling t-shirts :)
Wikipedia model, where the service is running based on donations, has also been considered. Wikipedia is one of the most visited websites in the world and still it needs to keep the operations very lean in order to be able to maintain its operations. 27 Crags will never match the amount of users with Wikipedia, and we also believe that with the subscription model we are better able to provide high quality content, keep on improving the service and reward the topo makers from their hard work.