Seriously though, we did, if you had money you bought this board - it wasn't as bad as you might think, the old PDPs had core which didn't lose it's contents when you powered them off, usually the bootstrap was still there
Later I got to write a boot ROM which supported 5 different drive types (4 types of floppy from 3.5" to 8" and Winchester hard drives), complete with terminal prompt, multi-unit support and interupt handler. I got it to fit into 256 words (2 256x8 PROMS) with some trickery (I still recall being out of space by one word and needing 204 for a sector read command - finally, remembering I had 102 in a register from loading the BEV vector, shifting that up one saved a load and so got it to fit).