That's the thing. It's all about price. My current Samsung S20 phone is far more powerful than any of these retro handhelds. Even my 3 year old Samsung S8 is far more powerful. But that's comparing a $1000 phone with an $80 retro handheld, and that price difference just highlights what amazing value for money these newer ones are, especially the RG351P, which I got for £72. Amazing price really.

I I suspect you are the same. Although our smartphones are so much more powerful they are just not practical to play retro games on, and the physical controls of these little retro handhelds makes all the difference between watching a game running well and actually being able to play it.