Most came /with/ a case - but almost all commercially available computers had to be hand assembled by the end user. Within a year or two, mass marketed computers were common place. But pre 1977 there were not that many to choose from, and even fewer to pick that were as completed made as the Apple.

Products like the Altair 8800 certainly came in a case, but they were not able to receive keyboard input or output test to a CRT display without significant aftermarket modifications. (Or various S-100 expansion boards that were released later)