I'll say it again: there is no point in criticising philosophy unless you have (1) a better way of (2) answering the same questions.

Criticism could come in the form of showing that the questions shouldn't be asked for one reason or another. Or criticism could come in the form of showing that the questions cannot be answered with the available tools. For example, if I ran into a bunch of people trying to trisect an arbitrary angle using compass and straight-edge, I might show them that their tools are inadequate for the task. In principle, I could do that without having any replacement procedure. And yet, it seems that I have helped them out.

Such criticism would have at least the following point. If people are engaged in a practice that cannot accomplish what they aim to accomplish, then they are wasting resources. Getting them to redirect their energies to other projects -- perhaps getting them to search for other ways to satisfy their original aims (ways that might possibly work) -- would put their resources to work.