How is it not constructive to point out that the original comment is simply whataboutism? Just because another problem exists doesn't mean it is pointless to wo

How is it not constructive to point out that the original comment is simply whataboutism? Just because another problem exists doesn't mean it is pointless to work on a related problem. Otherwise, one could easily make the point that climate change is a bigger problem than social isolation for older people, so any group attempting to alleviate that problem is wasting their time.