True for a given value of true...
"In 1978 64K was 'all you will ever need', or 48K for Apple II."
In 1978, 64K RAM was more than the typical home microcomputer buyer would want to spend. RAM was pretty pricey in those days. Don't forget also that those early micros commonly used ROMs for OS and programming languages: Apple ][s had 16 bit addressing just like all the rest of the early 8 bit crowd and could therefore address 64K memory.
There were any number of single-board hex keypad LED output microcomputers of that era which used about 1K RAM and more advanced machines like the TRS-80 and Apple ][s were offered with 4K RAM (admittedly, they both ended up being kitted out with more than that as standard). But if you had much (much!) deeper pockets than the typical hobbyist had and could splurge on a really big machine like a Cray 1 (first delivery of a trial machine in 1976), you could be looking at a 64 bit processor (data side, anyway) and over 8 megabytes of RAM - and a very big electricity bill.