People forget that Apple's first laptop had a trackball, not a touchpad:
https://www.macworld.com/article/229228/the-evolution-of-app...
There was also a laptop with this mouse "thing" that pulled out of the right side. Not Apple, I can't remember who made it.
Keyboards with integrated mice, trackballs and touchpads have been done a million times. You can buy them today in many forms (switch to image search to see the options):
https://www.google.com/search?q=keyboard+with+integrated+mou...
That said, trackpads are horrible things. They exist because they are massively cheaper to integrate into laptops than trackballs or having to ship something like a docking mouse, etc. They also reduce mechanical complexity and likely less issues on many other fronts.
In other words, trackpads are a huge win for manufacturers and a massive UI/UX loss for users.
Sure, for occasional browsing or low intensity tasks, no problem. Anything works. The little pointing gizmo on my Lenovo is there for when I have no other option. However, for anything that requires some level of complexity or performance on quickly learns trackpads just don't work. For me this means CAD, coding, applications like Excel, graphics work, etc. I use a thumb-operated trackball, have been doing so for decades. If I was forced to use a trackpad every day and had no other choice I would take a sledge hammer to the computer...that's no way to live.
I would imagine gamers have a similar opinion. I used to play games like Doom and Duke Nukem bak in the day. My performance using a trackball, when compared to others using mice of the era was just impossible to beat.