It is a matter of degree. Anytime you don't have a good match between the output stage and the antenna, the SWR goes up, how high depends on the mismatch. Anything short of full up (assuming the antenna was properly tuned to begin with) causes a rise in SWR. The higher the SWR, the more heat dissipated in the final stage. I do believe that most of our transmitter manufactures know that there will be much miss use of the equipment and try to design in some factor of oversight on our part. If they did not, most of us would have ruined our transmitters many times over. Just remember, failure rates approximately double for every 10 degrees Centigrade that the temperature increases for most electronic components.