It does go without saying, unless you are in a forum discussion about ETTR when some have to come up with reasons it is not going to work well. But you and I both know that we are not always in ideal conditions. No one in their right mind would invoke motion blur when not wanted just to provide more photons to the sensor! IF the conditions can be met, using ETTR, a Tripod, Mirror lock up, the best lens etc will produce the best (better) data than not using these techniques. And as image creators who understand the processes, I can’t see why we’d ignore better quality data if we can produce it. But there are all kinds of situations where I can’t use a tripod, or lock the mirror, or even ETTR to get an acceptable if not idelized data.
Yes of course - the key point in the context of this thread being that having conditions where ETTR can't be used to advantage isn't a valid argument for asserting that it shouldn't be used altogether or only under unreasonably limited conditions.