Owning a baseball bat generally doesn't make someone a skilled ball player ...
Owning a musical instrument generally doesn't make someone a musician ...
Owning a light source that attaches to a weapon generally won't imbue someone with the necessary skills and knowledge of the appropriate employment of the attached light ...
FWIW, I've seen ordinary folks suddenly unable to properly and effectively use an ordinary flashlight when subjected to unexpected stressful situations.
Training can be a good thing. Proper training can be even better.
There's a concept called "Low Frequency/High Risk" discussed in some risk management training. Forgive me if I paraphrase and oversimplify things, but think of it from the perspective of time-compressed, high liability situations which don't occur very often and which are often neglected when it comes to preparation and suitable training beforehand.
Having to suddenly come up with the right decision and action under the duress of such an infrequent situation may not result in the best reaction to the circumstances. Not the best way to mitigate, or attempt to minimize exposure to, potential liability from a risk management perspective.
The other instances, such as "High Frequency/Low risk", "Low Frequency/Low Risk" & "High frequency/High Risk" may arguably have potentially less risky outcomes.
Why?
"High Frequency/Low risk" - Non risky things we do every day and for which we're often experienced, well versed and knowledgeable. Probably not very stressful for reasons of low risk and frequent occurrence. Practiced, successful decision-making experience to fall back upon.
"Low Frequency/Low Risk" - Things we don't do every day, but which are of low risk. Probably less stress involved for many folks. No dire consequences if we make the wrong decision. Choose something we discover we dislike on a new luncheon menu and the world won’t stop revolving.
"High frequency/High Risk" - Risky things for which we're trained and well-versed. Situations and circumstances which we may anticipate and/or expect to occur on a frequent basis, and/or which we may do with high frequency, at least in training, remaining properly trained and currently experienced. Proper preparation, training and even actual experience may hopefully reduce the potential for confusion during actual situations, as well as inappropriate responses and actions.
Yeah, it's dangerous, but we frequently train for it, anticipate it and may even have experienced the actual event with some frequency, so it's also something which isn't as likely to 'surprise' us. Hence, our decision-making skills under stress will hopefully remain sufficiently current and appropriate to the tasks.
Now, which of those situational descriptions do you think might most closely describe someone without training attempting to employ a weapon-mounted light in a residential structure during a potentially life-threatening situation?
With individual responsibility for determining a course of action comes the very real potential for facing the consequences of that action ...
These sorts of decisions might arguably require some careful research and thought before implementation. Then, there's that proper training issue, as well. Trying to remember advice gleaned from the internet during the midst of an unexpected stressful, potentially life threatening situation isn't likely to go as well as someone might wish.
Not everyone is likely to agree on everything and that's not uncommon.
Even if a decision is made in favor of a weapon-mounted light within a certain situation or circumstances, there's the consideration of the type of equipment, especially regarding its operation and function.
Now, admittedly, I'm fortunate in that my job permits me access to a wide range of equipment which I can try out at the expense of my agency, someone else's agency, or a manufacturer/vendor evaluation sample. I've certainly tried some light equipment for which I'd never spend my own money.
Trying various equipment out during a classroom venue can be helpful before you spend hard-earned money on something. It might also help you determine whether a weapon-mounted light is even something for which you might have an appropriate use. Helps to find out beforehand if the presence of the added equipment adversely affects the functioning of the weapon in the hands of the particular user/owner, too.
Picture this situation ....
Suddenly illuminating something/someone which should not be fired upon (deadly force) - with a weapon-mounted light source - under the accumulating physical & mental stress of a perceived life-threatening situation (which may or may not exist, in the final result). Now, being startled by anything at this point can be a very, very dangerous situation for all concerned.
The potential adverse results of 'hand/finger confusion' can potentially be most unwanted and unfortunate.
Just my own thoughts, and I'm certainly nobody's expert ...