Not on other forums I've used that have this feature.
The visual noise part is a matter of personal preference, of course.
But thanks systems do get abused a lot in my experience on random forums that I find from time to time through search.
Just google "begging for thanks on forums" and you will see lots of forums with a topic discussing how annoying this begging is.
Also, on stackoverflow and others begging for points is even more prominent, since it gives some benefits, I believe.
You give people a measurable number and they will want to make it go up.