aeroconejo,
I don't make the rules .. however, I am required to apply them and one is that there are no links to overtly commercial sites. My application of this is to do the minimum edit practicable to achieve the policy's requirement.
If you have difficulty with that then I invite you to discuss the matter with this site's owners.
Fact of life is that this site costs lots to keep up and running and the owners' view is that commercial sites can make a contribution to this site's operating costs via advertising. Given that others advertise on this site, free plugs create a problem.