OK, so imagine a world where traders don't just trade based on news and words, but based on price signals. They have bots sitting there waiting for some criteria only in the price of the target asset, and they're going to trade on that. Let's say you know about this and you know how to give them the signals they need to make their trades, so you do things to give those signals so you can profit on their activity.

This world is real and you live in it. Does giving a price signal to the market count as making a stock go up or down based on what you said?

Taken to it's natural conclusion, every decision every market participant makes affects the market, and every speculative participant uses these impacts as criteria for their decisions. To some degree, every single market participant, whether they want to or not, is doing both 1) impacting the market in some way, and 2) trying to find actions other people are taking that will impact the market that they can enter and benefit from. It's a big positive feedback loop. What you're talking about, taken to it's natural conclusion, is just banning trading.