I think the point is that history on this forum has shown that users that damage and brick their phones due to irresponsible changes do not take responsibility for their own actions. When users bricked their phones the majority did not go "Eh, I knew the risks. Guess it is time to buy another phone." Instead they went to some lengths to hide that they caused the original failure, usually by damaging it further such that the original problem could not be detected. If this were not the case I doubt there would be even the slightest objection to overclocking or any other modification.
Put another way the members of the forum have shown a lack of willingness to be accountable for their own actions. Based on this tendency, actions that can cause damage more easily can be deemed objectionable because it makes support more expensive for HTC and as a consequence harder for end users to get support for changes that are unlikely to cause hardware damage (such as Cyanogen's ROM).
That is exactly what I was getting at. You just said it more eloquently.