This is a difficult subject, but may echo or confirm a number of other
peoples' observations. In any group tasked with a project, be it volunteer
or professional, individual members are able to produce different amounts
of work and/or function at varying levels of efficacy. Remedial efforts
are often made to teach those lagging how to work smarter, faster, to
better understand what they're trying to accomplish, etc and those efforts
usually help the group as a whole move forward and become more effective.
However, there are times when individuals simply cannot measure up to what is needed from them, despite any amount of training or being shown examples and given specific simple tasks that anyone should be able to do. In professional circles, such people are eventually fired or reallocated. In volunteer circles, they are usually given credit for at least trying somewhat and/or retasked with something else that may engage them or more appropriately match their achievement level.
In certain instances we appear to have some totally hopeless situations. Volunteers who have no technical skills and cannot or will not learn, who perhaps finish about a quarter of any simple task given to them and so badly that someone else needs to redo it, and who otherwise just stand around watching everyone else work. They'll consistently eat the free food, hold ladders and structures that don't need to be held, rack up arguably undeserved hours for the free membership, and offer profoundly inane, irrelevant commentary. They either remain fairly peripheral to the central activity or just get in the way, and if brought into any more complex aspect of the project can actually become a *liability* to the group. They can't lift anything, have no concept of balance or motion dynamics or logistical organization, and cannot be trusted to handle equipment properly and safely. And the real kicker is a general refusal or inherent inability to improve.
What can be charitably done about such elements? If I was a manager type, I might have some idea about how to extract usefulness from uselessness elsewhere, but I'm not a manager or division-head or anything like that so here's where I cut through the obfuscation and BS. Don't get me wrong, an *intent* to be a volunteer in almost any capacity is appreciated, but there are contexts in which it just doesn't work out. Our projects aren't the special olympics. This is real production under real time pressure, and there's really no place for drones who float around and just occupy space -- it just diminishes the overall capability of the group. That's not the charitable thing to say, I understand that and do regret having to bring it out, but it's not my job to come up with solutions to such problems. I'm generally too busy getting stuff done, learning, and trying to teach others even if I'm sometimes a little short about it. But the bottom line is, the time has come when I need to have a hard line taken and such elements moved permanently OUT of our workspaces before someone actually gets hurt or stuff gets damaged.
That's all I'm going to say on the matter, and leave it up to others with better people skills to come up with the best implementation.