One can't escape the apparent logic of recording the number of bird species seen within a designated perimeter and to repeat the procedure at regular intervals. Field biologist have been doing that sort of tallying since the brewing of coffee was perfected. The congruity between high numbers of individuals in a given area and the health of the population at large helped determine which species were endangered or at risk. Too great a tally might indicate another problem entirely. There are many people on this planet but the human population may not actually be that healthy, mentally or physically, nor is the planet that hosts us rosy-cheeked.
The birds that visit a backyard are generally the most populous, most successful and most adaptable species that have somehow managed to thrive in an urban environment. These bird species represent a subset of birds in general that have come to tolerate their observers. The conditions we have created in our little castles, or rooms within a bigger castle, are aberrational transformations of the wilds that are so far removed from what might be construed as the planet's backyard that it's like counting the bacteria in a petri dish and then assuming that is a fair and wholesome reflection of the surface of the kitchen table. At best, a backyard bird count scaled up to a phenomena helps to get receptive people's head out of their backside, their troubles, their routines and stretch their crippled attention span into a healthier lengthier heightened awareness mode so that they can pay some sort of tribute to another life form. We'll likely never have a Great Backyard Bear Count anytime soon. Oh, oh, oh, I know ... this is Canada, ... a Great Backyard Beaver Count! No, it don't work. My backyard may look at little wild, but it's not WILD! How many beaver could there be? Ok then, bird count it is.