Nope. I do not agree with you. I'm a frequent traveler and was sitted next to a huge guy. I did not make a fuss as I do not want to embarass the guy. However, I was extremely uncomfortable and wrote to the CSR. I was told that passengers "volunteer" the information (about their size) upfront and are required to buy two seats. If the passengers do not give this information, there is nothing Delta can do about it. I told Delta that clearly it can stop the customer from boarding and that the CSR at the gate should be able to "see" a passenger will not be able to fit into the seat. No replies from Delta after that.
If you are in a situation where the flight is full, you have no other choice but to bear with it if you want to go home. If not, you can always opt for other flights (Delta told me I have this option if I raised it to the CSR at that time). Hmmm....I wondered if I objected to the huge guy sitting next to me, who will be left to take another flight???