They didn't need to create a new app. At the same time that they started adding LLM garbage to Notepad, they discontinued WordPad.

https://en.wikipedia.org/wiki/Windows_Notepad#Change_in_deve... https://en.wikipedia.org/wiki/WordPad#Discontinuation

They likely knew nobody would be drawn to WordPad by the additions, so they had to scavenge their rapidly diminishing list of actually useful software for sacrifices on the altar to their outrageous AI investments.