I'm not talking about the Cintiq. Around 2015 I was daily driving an HP elite book 2760p which couldn covert to a tablet and had Wacom EMR tech integrated into the display. It worked fine for drawing and I did a lot of it. Along with Fujitsu and Lenovo they'd been making them since the core 2 duo era at least. When the surface pro came out it was building on these, and then the Apple pencil competed with the surface pro. These products sold then and still sell today. At my current company, the default windows laptop is a Thinkpad yoga with a stylus. I'll take your word for it when you say that the Apple pencil was an improvement and sold better. But Apple didn't invent this. There were absolutely successful products that came before.

"There were absolutely successful products that came before"

I think it's just a question of definition. The Apple pencil was introduced in 2016, since then about 500.000.000 iPads have been sold. If you compare that with the number of Thinkpad yogas or HP elite book 2760ps it's possible to come the conclusion that they are relatively less successful. But of course they can be "absolutely successful" depending on your definition.