Earlier quoted context omitted.
This is not passive income. This is asset appreciation. Dividends or rent collection qualify as passive income.
Can you explain why you differentiate the two (price changes vs dividends)? AFAIU it’s really just that you have to instruct one to be sold to realize it and the other just shows up in your account, but the overall returns, tax implications, and such are basically the same.
More technical reasons follow.
The risk profile is very different. Rents, dividends, and interest payments all have some notion of a guaranteed payment. Your risk is primarily whether your counter party will be able to honor that agreement. This is why bond investing is often called "fixed income" because you know ahead of time how much money you'll make.
Asset appreciation has immense market risk. You need to find a buyer willing to pay more for what you paid for it. In the case of companies the economic risk are higher too: if the companies cashflows dwindle or debt increases the shares are fundamentally worth less.
This is why there are often tax distinctions between guaranteed income streams and capital investments: in theory, a government wants to encourage investment in risk and discourage printing guaranteed monthly checks. This does create a regulatory arbitrage, however, where companies can buy fixed amounts of their own stocks to guarantee some amount of appreciation in lieu of a dividend.