Krita is not targeted as a photoshop replacement. It was at one time, but 15+ years ago they realized that many people are willing to pay for photoshop and thus Adobe has a large amount of money to throw at developers (at least some of them good) and so they are unlikely to catch up. They then shifted focus to be the best programing for drawing instead, a niche that Photoshop can cover but it isn't what their customers want and so it isn't well served. Photoshop is mostly used by photographers who need to touch up a photo, this is art but a very different style of art from someone who starts with a blank page and draws a picture.
