That's true to some degree, but as somebody who actually used remote streaming fairly extensively in the past (from PC to PC), it's not exactly trouble-free. The most common problem I remember having is that not every game was super friendly to image capture, which is obviously required to actually make the stream. I remember some outright crashing or failing to capture in the worst cases, but also others which did work yet suffered performance issues (especially if the resolution on your PC was high). Sometimes the frame time wasn't smooth despite everything running at 60FPS, due to the game doing whatever VSync fuckery it wouldn't let you configure or fuck knows what.
Also if you're going to be streaming to a phone like that, or any device with an aspect ratio different than your PC monitor, the game may not offer a resolution in the aspect ratio of your client. This means you may get black bars on your client and a resolution in the right AR may not be immediately available in the game options. You can often fix this with a custom res and shit on your PC, but it's kind of a pain because some games may just not support it even if you make a custom res. With a small screen like a phone, you can also run into readability issues with text, like the phone screen may not be big enough for text which is intended to show up on a large monitor. There are a lot of different little issues like that which can crop up.
Controls are also another issue. Small phone clamp-on controllers like that are total shit if you're an adult. They're too small for adult hands and you're going to get cramps in like 30 minutes of any seriously engaging game, the bigger handhelds have an advantage simply due to being big enough to have more ergonomic controls (Steam Deck is especially good at this despite it being kinda outdated in terms of performance).