You can also remap most shortcuts to the keys you wantBetter too many shortcuts than too few. Nobody forces you to use or memorize them. And for those of us who prefer keyboard control, having to use the mouse for more than we already do would suck.
Screenshots taken using key shortcuts are typically saved on your desktop. However, if you tack the Control key onto either of these shortcuts, macOS will copy the captured image to the clipboard instead of saving it as a file on your desktop, which is useful if you want to paste it into an application that can edit or view images, or use Universal Clipboard to paste it on another Apple device.
These keystrokes have been around for 20+ years. Apple isn't suddenly make it harder just recently.
These keystrokes used to be the _only_ way to capture screenshots (natively), but they more recently added the Screenshot app, as discussed in this article, for those that struggle with keystrokes.