As long as you are occupying a residence, it would not effect nationwide or region-wide supply and demand, right? You selling would be offset by you buying.
Deaths, divorces, immigration, births, and of course, new construction is what would shift supply and demand curves, on average.
Also, if lots of people are buying and selling, even if aggregate demand is the same, it's a more liquid market. If I'm a first-time homebuyer, I'd rather play in a market of musical chairs then try to buy in a theater where only the dead and divorced get up from their seats.
If a family that would normally have sold their older two bedroom and moved to a four bedroom instead chooses to remain in the two bedroom longer, that two bedroom doesn't appear on the market, a four bedroom languishes.
And if nobody is building two bedroom houses, that can have ripple effects.