Well, yeah.
First of all, there are SO MANY BOARDS you can buy now. Not just cheap clones and poorly documented boards from China, but also cheap manufacturer-provided boards like the TI Launchpads and ST Nucleo boards.
Secondly, you can't really get much beyond am ATmega1284 and still be in the realm of "comfortable" home construction. Oh, it might be possible to hand solder those fine-pitch high-density high pin-count 32bit microcontrollers and 603 or smaller passive components, but it's certainly perceived as being much more difficult than TH chips.
Thirdly, we're sorta past the "you can design a board and everyone will use it and everything will be swell!" stage of things, and it's becoming more obvious just how much work is involved in ... all stages ... of such a project.