It's not entirely useless, or it would be useless to discuss it.

But its utility is limited, for reasons already discussed. Nor it is entirely free of potential harm. Overestimating the utility or underestimating the potential for harm are both dangerous.

@P-Funk: which stakeholders are the network? Because this set potentially changes every time there is a transaction. Polls and voting can only measure stakeholders at an instant-in-time, but both network stability and confidence in the economic value require a greater degree of stability and consensus over acceptable rules and rule changes. That is why, for example, soft forks typically require a large supermajority. There is no technical difference between a soft fork supported by 51% of the network and a 51% attack; the only difference is that an acceptable soft fork is widely supported by the larger community and a 51% attack is not. But technically, and in terms of on-chain voting, the two are identical.