RE:RE:RE:London TXP shorting position update.......Sometimes selling short is not trying to create a false market and drive shares down.
You buy a stock because you have reasons to think that it is undervalued and will continue do well and its shares will go up. Or maybe you expect some success that could be very positive but is not certain to happen. Buying it doesn't not necessarily make it go up. However the share price can be "pumped' and artificially inflated by those who hope to dump it later to make a quick profit.
Similarly you sell a stock because you have reasons to think it is overvalued and will go down. Or because you think that some anticipated success is not going to pan out. Selling the shares does not necessarily make it go down. However concerted or coordinated selling coupled with trashing of the company can artificially drive it done so those actors can buy it much lower and make a quick profit.
Selling shares that are overvalued allows you to profit if that is an accurate assessment and the shares return to a more reasonable valuation. You will also profit if the company has unanticipated bad news (or fails to achieve anticipated good news) and that outcome negatively alters their prospects.
Selling shares also serves a useful purpose as an antidote to the "pump and dump scenario" described above, by putting a damper on it.
So in general buying and selling (even short selling) of shares both contribute to an efficient market and help prevent excesses in either direction. At least that is the theory. If it was as simple as you describe (creating a false market and pushing share price down) they would just eliminate it.