Yes, but I don't consider a clipped (saturated) signal to be useful.
It is up to the photographer to decide what is "important" to retain in the highlights. For example, it may be fine (even desirable) to clip some specular reflections to pure white -- no detail recorded in those areas. In other cases, it may be desirable to keep the full range of highlights. This may make it difficult or impossible to increase the exposure further.
So, to clarify: the motivation behind ETTR is all about maximizing signal-to-noise, but in the field ETTR cannot always be used for all situations.
We seem to be confusing the 'objective' with the 'subjective', which is why I would consider my definition to be more precise because it includes both the objective and the subjective, ie. ""Setting the exposure to maximise signal-to-noise whilst simultaneously retaining full detail in all highlights in the scene that one considers important."
What one considers important is a subjective assessment. Setting exposure to maximise the total number of levels captured in the scene could be considered as the basic, objective definition of ETTR, which is a good starting point.
The obvious example, which I've used before somewhere, is a scene of wildlife in the shade of a tree with significant areas of sky visible through the branches. One photographer thinks the sky (its detail or its color) is sufficiently interesting to retain, and increases his shutter speed accordingly. Another photographer decides to use a slower shutter speed to reduce noise in the main subject which he considers is the bird or wildlife, at the risk perhaps of failing to freeze movement.
It makes little sense from an objective perspective to describe both exposures, which may differ significantly, an ETTR. From an objective perspective, the shot that retains detail in the sky, to point of near clipping, is an ETTR. The other shot is a deliberate overexposure for esthetic or subjective reasons.